From 3dd9e63881344e08ccf78cf0e314990d13bb3b20 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 10:34:25 +0100
Subject: [PATCH 01/25] New: init version of plugin feature with template parts

---
 includes/classes/BrandedEmails.php            | 49 +++++++++++++++++++
 includes/classes/Templates.php                | 48 ++++++++++++++++++
 orbit.php                                     |  1 +
 .../branded-emails/email-template.php         | 45 +++++++++++++++++
 4 files changed, 143 insertions(+)
 create mode 100644 includes/classes/BrandedEmails.php
 create mode 100644 includes/classes/Templates.php
 create mode 100644 template-parts/branded-emails/email-template.php

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
new file mode 100644
index 0000000..c307937
--- /dev/null
+++ b/includes/classes/BrandedEmails.php
@@ -0,0 +1,49 @@
+<?php
+/**
+ * Add branding email templates to site emails.
+ *
+ * @package         Orbit
+ */
+
+namespace Eighteen73\Orbit;
+
+/**
+ * This class is built upon BE Media from Production so all due credit to those authors.
+ * http://www.github.com/billerickson/be-media-from-production
+ */
+class BrandedEmails {
+
+	use Environment;
+	use Singleton;
+	use Templates;
+
+	/**
+	 * Primary constructor
+	 *
+	 * @return void
+	 */
+	public function setup() {
+		if ( apply_filters( 'orbit_disable_branded_emails', false ) ) {
+			return;
+		}
+
+		add_filter( 'wp_mail', [ $this, 'apply_branded_email_template' ] );
+	}
+
+	public function apply_branded_email_template( $args ) {
+		ob_start();
+
+		Templates::include_template_part(
+			'branded-emails/email-template.php',
+			[
+				'email_content' => $args['message'],
+			]
+		);
+
+		$styled_message = ob_get_clean();
+
+		$args['message'] = $styled_message;
+
+		return $args;
+	}
+}
diff --git a/includes/classes/Templates.php b/includes/classes/Templates.php
new file mode 100644
index 0000000..7cc2322
--- /dev/null
+++ b/includes/classes/Templates.php
@@ -0,0 +1,48 @@
+<?php
+/**
+ * Template functions for Orbit.
+ *
+ * @package         Orbit
+ */
+
+namespace Eighteen73\Orbit;
+
+/**
+ * This class is built upon BE Media from Production so all due credit to those authors.
+ * http://www.github.com/billerickson/be-media-from-production
+ */
+class Templates {
+
+	use Environment;
+	use Singleton;
+
+	/**
+	 * Function to get the template file from the theme if it exists, otherwise from the plugin.
+	 *
+	 * @param string $template_name The name of the template file.
+	 * @return string The path to the template file.
+	 */
+	private static function get_template_part( $template_name ) {
+		$theme_template = get_stylesheet_directory() . '/template-parts/' . $template_name;
+
+		if ( file_exists( $theme_template ) ) :
+			return $theme_template;
+		endif;
+
+		return ORBIT_PATH . 'template-parts/' . $template_name;
+	}
+
+	/**
+	 * Function to include the template file from the get_template_part function.
+	 *
+	 * @param string $template_name The name of the template file.
+	 */
+	public static function include_template_part( string $template_name, array $args = [] ) {
+
+		$template_path = self::get_template_part( $template_name );
+
+		extract( $args );
+
+		include $template_path;
+	}
+}
diff --git a/orbit.php b/orbit.php
index c897575..0dbcbea 100644
--- a/orbit.php
+++ b/orbit.php
@@ -45,6 +45,7 @@ function () {
 		Security\HideAuthor::instance()->setup();
 		Security\HideVersion::instance()->setup();
 		Security\RemoveHeadLinks::instance()->setup();
+		BrandedEmails::instance()->setup();
 		OtherFilters::instance()->setup();
 		HealthCheck::instance()->setup();
 		RemoteFiles::instance()->setup();
diff --git a/template-parts/branded-emails/email-template.php b/template-parts/branded-emails/email-template.php
new file mode 100644
index 0000000..7ce78b4
--- /dev/null
+++ b/template-parts/branded-emails/email-template.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * Global Email Template
+ * This file can be overridden in your theme.
+ *
+ * Available variables:
+ * @var string $email_content
+ */
+
+?>
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="UTF-8">
+  <style>
+    body {
+      font-family: Arial, sans-serif;
+      background: #f4f4f4;
+      padding: 20px;
+    }
+    .email-wrapper {
+      background: #ffffff;
+      padding: 20px;
+      border: 1px solid #ddd;
+      border-radius: 6px;
+      max-width: 600px;
+      margin: 0 auto;
+    }
+    .email-footer {
+      margin-top: 20px;
+      font-size: 12px;
+      color: #999;
+      text-align: center;
+    }
+  </style>
+</head>
+<body>
+  <div class="email-wrapper">
+    <?php echo wpautop($email_content); ?>
+    <div class="email-footer">
+      Sent from <?php echo esc_html(get_bloginfo('name')); ?>
+    </div>
+  </div>
+</body>
+</html>

From 4362651f5abd78d1deddfd0c41524a394a9a909e Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 10:39:30 +0100
Subject: [PATCH 02/25] Fix: tried to use class as a trait

---
 includes/classes/BrandedEmails.php | 1 -
 1 file changed, 1 deletion(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index c307937..bcde4b9 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -15,7 +15,6 @@ class BrandedEmails {
 
 	use Environment;
 	use Singleton;
-	use Templates;
 
 	/**
 	 * Primary constructor

From f8dab27a67f00222d47eb295212ee4697bbd47e8 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 11:09:26 +0100
Subject: [PATCH 03/25] New: add styles as separate file

---
 includes/classes/BrandedEmails.php            |  6 +++
 .../branded-emails/email-styles.php           | 41 +++++++++++++++++++
 .../branded-emails/email-template.php         | 35 +++++-----------
 3 files changed, 58 insertions(+), 24 deletions(-)
 create mode 100644 template-parts/branded-emails/email-styles.php

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index bcde4b9..16a0ceb 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -29,6 +29,12 @@ public function setup() {
 		add_filter( 'wp_mail', [ $this, 'apply_branded_email_template' ] );
 	}
 
+	/**
+	 * Wraps the original email message in a branded HTML email template.
+	 *
+	 * @param array $args Array of arguments passed to wp_mail().
+	 * @return array Modified $args array with the email message wrapped in branded HTML.
+	 */
 	public function apply_branded_email_template( $args ) {
 		ob_start();
 
diff --git a/template-parts/branded-emails/email-styles.php b/template-parts/branded-emails/email-styles.php
new file mode 100644
index 0000000..b1aa8ad
--- /dev/null
+++ b/template-parts/branded-emails/email-styles.php
@@ -0,0 +1,41 @@
+<?php
+/**
+ * Branded Email Styles
+ * This file can be overridden in your theme.
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly.
+}
+
+$background_color = apply_filters( 'orbit_branded_emails_background_color', '#f4f4f4' );
+$body_background_color = apply_filters( 'orbit_branded_emails_body_background_color', '#ffffff' );
+$body_border_color = apply_filters( 'orbit_branded_emails_body_border_color', '#ddd' );
+$body_max_width = apply_filters( 'orbit_branded_emails_body_max_width', '800px' );
+$body_text_color = apply_filters( 'orbit_branded_emails_body_text_color', '#000' );
+$footer_text_color = apply_filters( 'orbit_branded_emails_footer_text_color', '#999' );
+?>
+
+<style>
+    body {
+		background: <?php echo esc_attr( $background_color ); ?>;
+		padding: 20px;
+    }
+
+    .email-wrapper {
+		background: <?php echo esc_attr( $body_background_color ); ?>;
+		border: 1px solid <?php echo esc_attr( $body_border_color ); ?>;
+		border-radius: 6px;
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		max-width: <?php echo esc_attr( $body_max_width ); ?>;
+		margin: 0 auto;
+		padding: 20px;
+    }
+
+    .email-footer {
+		color: <?php echo esc_attr( $footer_text_color ); ?>;
+		font-size: 12px;
+		margin-top: 20px;
+		text-align: center;
+    }
+</style>
diff --git a/template-parts/branded-emails/email-template.php b/template-parts/branded-emails/email-template.php
index 7ce78b4..035e0fb 100644
--- a/template-parts/branded-emails/email-template.php
+++ b/template-parts/branded-emails/email-template.php
@@ -1,44 +1,31 @@
 <?php
 /**
- * Global Email Template
+ * Branded Email Template
  * This file can be overridden in your theme.
  *
  * Available variables:
  * @var string $email_content
  */
 
+namespace Eighteen73\Orbit;
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly.
+}
+
 ?>
 <!DOCTYPE html>
 <html>
 <head>
   <meta charset="UTF-8">
-  <style>
-    body {
-      font-family: Arial, sans-serif;
-      background: #f4f4f4;
-      padding: 20px;
-    }
-    .email-wrapper {
-      background: #ffffff;
-      padding: 20px;
-      border: 1px solid #ddd;
-      border-radius: 6px;
-      max-width: 600px;
-      margin: 0 auto;
-    }
-    .email-footer {
-      margin-top: 20px;
-      font-size: 12px;
-      color: #999;
-      text-align: center;
-    }
-  </style>
+  <?php Templates::include_template_part( 'branded-emails/email-styles.php' ); ?>
 </head>
 <body>
   <div class="email-wrapper">
-    <?php echo wpautop($email_content); ?>
+    <?php echo wpautop( $email_content ); ?>
+
     <div class="email-footer">
-      Sent from <?php echo esc_html(get_bloginfo('name')); ?>
+      Sent from <?php echo esc_html( get_bloginfo('name') ); ?>
     </div>
   </div>
 </body>

From 558fbc5ee14c4202b180dce00c69d7970bff41dc Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 12:36:40 +0100
Subject: [PATCH 04/25] New: only apply template to non html emails, specific
 gf scenario

---
 includes/classes/BrandedEmails.php            | 53 +++++++++++++++++++
 .../branded-emails/email-template.php         | 25 ++++-----
 2 files changed, 66 insertions(+), 12 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 16a0ceb..1f54da2 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -27,6 +27,7 @@ public function setup() {
 		}
 
 		add_filter( 'wp_mail', [ $this, 'apply_branded_email_template' ] );
+		add_filter( 'gform_html_message_template_pre_send_email', [ $this, 'apply_branded_email_template_to_gf_notifications' ] );
 	}
 
 	/**
@@ -36,19 +37,71 @@ public function setup() {
 	 * @return array Modified $args array with the email message wrapped in branded HTML.
 	 */
 	public function apply_branded_email_template( $args ) {
+		$headers = [];
+
+		// Convert headers to an array if they aren't already
+		if ( empty( $args['headers'] ) ) {
+			$headers = [];
+		} elseif ( is_string( $args['headers'] ) ) {
+			$headers = explode( "\n", str_replace( "\r\n", "\n", $args['headers'] ) );
+		} elseif ( is_array( $args['headers'] ) ) {
+			$headers = $args['headers'];
+		}
+
+		// Check if Content-Type is already set to HTML
+		$content_type_is_html = false;
+		foreach ( $headers as $header ) {
+			if ( stripos( $header, 'Content-Type:' ) !== false && stripos( $header, 'text/html' ) !== false ) {
+				$content_type_is_html = true;
+				break;
+			}
+		}
+
+		// If email is already HTML return original $args
+		if ( $content_type_is_html ) {
+			return $args;
+		}
+
 		ob_start();
 
 		Templates::include_template_part(
 			'branded-emails/email-template.php',
 			[
 				'email_content' => $args['message'],
+				'email_subject' => isset( $args['subject'] ) ? $args['subject'] : '',
 			]
 		);
 
 		$styled_message = ob_get_clean();
 
+		// Remove existing Content-Type headers (at this point we've already established it's not HTML)
+		$headers = array_filter( $headers, function ( $header ) {
+			return stripos( $header, 'Content-Type:' ) === false;
+		} );
+
+		// Add HTML Content-Type
+		$headers[] = 'Content-Type: text/html; charset=UTF-8';
+
+		// Set updated headers and message
+		$args['headers'] = $headers;
 		$args['message'] = $styled_message;
 
 		return $args;
 	}
+
+	public function apply_branded_email_template_to_gf_notifications( $template ) {
+		ob_start();
+
+		Templates::include_template_part(
+			'branded-emails/email-template.php',
+			[
+				'email_content' => '{message}',
+				'email_subject' => '{subject}',
+			]
+		);
+
+		$template = ob_get_clean();
+
+		return $template;
+	}
 }
diff --git a/template-parts/branded-emails/email-template.php b/template-parts/branded-emails/email-template.php
index 035e0fb..74f4c62 100644
--- a/template-parts/branded-emails/email-template.php
+++ b/template-parts/branded-emails/email-template.php
@@ -16,17 +16,18 @@
 ?>
 <!DOCTYPE html>
 <html>
-<head>
-  <meta charset="UTF-8">
-  <?php Templates::include_template_part( 'branded-emails/email-styles.php' ); ?>
-</head>
-<body>
-  <div class="email-wrapper">
-    <?php echo wpautop( $email_content ); ?>
+	<head>
+		<meta charset="UTF-8">
+		<title><?php echo esc_attr( $email_subject ); ?></title>
+		<?php Templates::include_template_part( 'branded-emails/email-styles.php' ); ?>
+	</head>
+	<body>
+		<div class="email-wrapper">
+			<?php echo wpautop( $email_content ); ?>
 
-    <div class="email-footer">
-      Sent from <?php echo esc_html( get_bloginfo('name') ); ?>
-    </div>
-  </div>
-</body>
+			<div class="email-footer">
+				Sent from <?php echo esc_html( get_bloginfo('name') ); ?>
+			</div>
+		</div>
+	</body>
 </html>

From 082551a5ae8ad935510655eff7989cefdfec2b88 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 12:50:56 +0100
Subject: [PATCH 05/25] New: add logo to template

---
 includes/classes/BrandedEmails.php             |  2 +-
 template-parts/branded-emails/email-styles.php | 11 +++++++++++
 .../branded-emails/email-template.php          | 18 ++++++++++++++++--
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 1f54da2..874a339 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -22,7 +22,7 @@ class BrandedEmails {
 	 * @return void
 	 */
 	public function setup() {
-		if ( apply_filters( 'orbit_disable_branded_emails', false ) ) {
+		if ( apply_filters( 'orbit_branded_emails_disable', false ) ) {
 			return;
 		}
 
diff --git a/template-parts/branded-emails/email-styles.php b/template-parts/branded-emails/email-styles.php
index b1aa8ad..1f30f7f 100644
--- a/template-parts/branded-emails/email-styles.php
+++ b/template-parts/branded-emails/email-styles.php
@@ -19,6 +19,7 @@
 <style>
     body {
 		background: <?php echo esc_attr( $background_color ); ?>;
+		font-family: "Helvetica Neue", Helvetica, Roboto, Arial, sans-serif;
 		padding: 20px;
     }
 
@@ -32,6 +33,16 @@
 		padding: 20px;
     }
 
+	.email-header img {
+		max-height: 100px;
+		width: auto;
+	}
+
+	.email-content {
+		margin-bottom: 40px;
+		margin-top: 40px;
+	}
+
     .email-footer {
 		color: <?php echo esc_attr( $footer_text_color ); ?>;
 		font-size: 12px;
diff --git a/template-parts/branded-emails/email-template.php b/template-parts/branded-emails/email-template.php
index 74f4c62..c08731c 100644
--- a/template-parts/branded-emails/email-template.php
+++ b/template-parts/branded-emails/email-template.php
@@ -13,6 +13,7 @@
 	exit; // Exit if accessed directly.
 }
 
+$header_logo = apply_filters( 'orbit_branded_emails_header_logo', '' );
 ?>
 <!DOCTYPE html>
 <html>
@@ -21,12 +22,25 @@
 		<title><?php echo esc_attr( $email_subject ); ?></title>
 		<?php Templates::include_template_part( 'branded-emails/email-styles.php' ); ?>
 	</head>
+
 	<body>
 		<div class="email-wrapper">
-			<?php echo wpautop( $email_content ); ?>
+			<div class="email-header">
+				<?php
+				if ( ! empty( $header_logo ) ) {
+					echo '<p style="margin-top:0;"><img src="' . esc_url( $header_logo ) . '" alt="' . esc_attr( get_bloginfo( 'name', 'display' ) ) . '" /></p>';
+				} else {
+					echo '<h1>' . esc_html( get_bloginfo( 'name' ) ) . '</h1>';
+				}
+				?>
+			</div>
+
+			<div class="email-content">
+				<?php echo wpautop( $email_content ); ?>
+			</div>
 
 			<div class="email-footer">
-				Sent from <?php echo esc_html( get_bloginfo('name') ); ?>
+				Sent from <?php echo esc_html( get_bloginfo('name', 'display') ); ?>
 			</div>
 		</div>
 	</body>

From b7c2db0ee46cf187b0fb7de68786b733322dab30 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 13:43:47 +0100
Subject: [PATCH 06/25] Fix: code sniffer fixes

---
 includes/classes/BrandedEmails.php             | 18 +++++++++++++++---
 includes/classes/Templates.php                 |  7 ++++---
 template-parts/branded-emails/email-styles.php | 14 ++++++++------
 .../branded-emails/email-template.php          | 10 +++++++---
 4 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 874a339..cf04405 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -75,9 +75,12 @@ public function apply_branded_email_template( $args ) {
 		$styled_message = ob_get_clean();
 
 		// Remove existing Content-Type headers (at this point we've already established it's not HTML)
-		$headers = array_filter( $headers, function ( $header ) {
-			return stripos( $header, 'Content-Type:' ) === false;
-		} );
+		$headers = array_filter(
+			$headers,
+			function ( $header ) {
+				return stripos( $header, 'Content-Type:' ) === false;
+			}
+		);
 
 		// Add HTML Content-Type
 		$headers[] = 'Content-Type: text/html; charset=UTF-8';
@@ -89,6 +92,15 @@ public function apply_branded_email_template( $args ) {
 		return $args;
 	}
 
+	/**
+	 * Provides a branded HTML template for Gravity Forms email notifications.
+	 *
+	 * `{message}` and `{subject}` placeholders will be replaced by
+	 * Gravity Forms with the actual notification content.
+	 *
+	 * @param string $template The original email template string (usually empty).
+	 * @return string The modified email template with placeholders for message and subject.
+	 */
 	public function apply_branded_email_template_to_gf_notifications( $template ) {
 		ob_start();
 
diff --git a/includes/classes/Templates.php b/includes/classes/Templates.php
index 7cc2322..6db2d52 100644
--- a/includes/classes/Templates.php
+++ b/includes/classes/Templates.php
@@ -36,13 +36,14 @@ private static function get_template_part( $template_name ) {
 	 * Function to include the template file from the get_template_part function.
 	 *
 	 * @param string $template_name The name of the template file.
+	 * @param array  $args          Optional. Associative array of variables to make available in the template.
 	 */
 	public static function include_template_part( string $template_name, array $args = [] ) {
 
 		$template_path = self::get_template_part( $template_name );
 
-		extract( $args );
-
-		include $template_path;
+		if ( file_exists( $template_path ) ) {
+			include $template_path;
+		}
 	}
 }
diff --git a/template-parts/branded-emails/email-styles.php b/template-parts/branded-emails/email-styles.php
index 1f30f7f..bf7c4ae 100644
--- a/template-parts/branded-emails/email-styles.php
+++ b/template-parts/branded-emails/email-styles.php
@@ -2,6 +2,8 @@
 /**
  * Branded Email Styles
  * This file can be overridden in your theme.
+ *
+ * @package         Orbit
  */
 
 if ( ! defined( 'ABSPATH' ) ) {
@@ -17,13 +19,13 @@
 ?>
 
 <style>
-    body {
+	body {
 		background: <?php echo esc_attr( $background_color ); ?>;
 		font-family: "Helvetica Neue", Helvetica, Roboto, Arial, sans-serif;
 		padding: 20px;
-    }
+	}
 
-    .email-wrapper {
+	.email-wrapper {
 		background: <?php echo esc_attr( $body_background_color ); ?>;
 		border: 1px solid <?php echo esc_attr( $body_border_color ); ?>;
 		border-radius: 6px;
@@ -31,7 +33,7 @@
 		max-width: <?php echo esc_attr( $body_max_width ); ?>;
 		margin: 0 auto;
 		padding: 20px;
-    }
+	}
 
 	.email-header img {
 		max-height: 100px;
@@ -43,10 +45,10 @@
 		margin-top: 40px;
 	}
 
-    .email-footer {
+	.email-footer {
 		color: <?php echo esc_attr( $footer_text_color ); ?>;
 		font-size: 12px;
 		margin-top: 20px;
 		text-align: center;
-    }
+	}
 </style>
diff --git a/template-parts/branded-emails/email-template.php b/template-parts/branded-emails/email-template.php
index c08731c..d930b2c 100644
--- a/template-parts/branded-emails/email-template.php
+++ b/template-parts/branded-emails/email-template.php
@@ -3,7 +3,8 @@
  * Branded Email Template
  * This file can be overridden in your theme.
  *
- * Available variables:
+ * @package         Orbit
+ *
  * @var string $email_content
  */
 
@@ -14,7 +15,10 @@
 }
 
 $header_logo = apply_filters( 'orbit_branded_emails_header_logo', '' );
+$email_content = $args['email_content'] ?? '';
+$email_subject = $args['email_subject'] ?? get_bloginfo( 'name', 'display' );
 ?>
+
 <!DOCTYPE html>
 <html>
 	<head>
@@ -36,11 +40,11 @@
 			</div>
 
 			<div class="email-content">
-				<?php echo wpautop( $email_content ); ?>
+				<?php echo wp_kses_post( wpautop( $email_content ) ); ?>
 			</div>
 
 			<div class="email-footer">
-				Sent from <?php echo esc_html( get_bloginfo('name', 'display') ); ?>
+				Sent from <?php echo esc_html( get_bloginfo( 'name', 'display' ) ); ?>
 			</div>
 		</div>
 	</body>

From 2407755c0312de2ae3fa902ab6add0f2bcbe46aa Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 4 Aug 2025 16:50:42 +0100
Subject: [PATCH 07/25] New: rename template functions and where they go in the
 theme

---
 includes/classes/BrandedEmails.php                    |  4 ++--
 includes/classes/Templates.php                        | 11 +++++------
 .../branded-emails/email-styles.php                   |  0
 .../branded-emails/email-template.php                 |  2 +-
 4 files changed, 8 insertions(+), 9 deletions(-)
 rename {template-parts => templates}/branded-emails/email-styles.php (100%)
 rename {template-parts => templates}/branded-emails/email-template.php (93%)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index cf04405..0c3380e 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -64,7 +64,7 @@ public function apply_branded_email_template( $args ) {
 
 		ob_start();
 
-		Templates::include_template_part(
+		Templates::include_template(
 			'branded-emails/email-template.php',
 			[
 				'email_content' => $args['message'],
@@ -104,7 +104,7 @@ function ( $header ) {
 	public function apply_branded_email_template_to_gf_notifications( $template ) {
 		ob_start();
 
-		Templates::include_template_part(
+		Templates::include_template(
 			'branded-emails/email-template.php',
 			[
 				'email_content' => '{message}',
diff --git a/includes/classes/Templates.php b/includes/classes/Templates.php
index 6db2d52..6db3870 100644
--- a/includes/classes/Templates.php
+++ b/includes/classes/Templates.php
@@ -22,14 +22,14 @@ class Templates {
 	 * @param string $template_name The name of the template file.
 	 * @return string The path to the template file.
 	 */
-	private static function get_template_part( $template_name ) {
-		$theme_template = get_stylesheet_directory() . '/template-parts/' . $template_name;
+	private static function get_template( $template_name ) {
+		$theme_template = get_theme_file_path( '//orbit//' . $template_name );
 
 		if ( file_exists( $theme_template ) ) :
 			return $theme_template;
 		endif;
 
-		return ORBIT_PATH . 'template-parts/' . $template_name;
+		return ORBIT_PATH . 'templates/' . $template_name;
 	}
 
 	/**
@@ -38,9 +38,8 @@ private static function get_template_part( $template_name ) {
 	 * @param string $template_name The name of the template file.
 	 * @param array  $args          Optional. Associative array of variables to make available in the template.
 	 */
-	public static function include_template_part( string $template_name, array $args = [] ) {
-
-		$template_path = self::get_template_part( $template_name );
+	public static function include_template( string $template_name, array $args = [] ) {
+		$template_path = self::get_template( $template_name );
 
 		if ( file_exists( $template_path ) ) {
 			include $template_path;
diff --git a/template-parts/branded-emails/email-styles.php b/templates/branded-emails/email-styles.php
similarity index 100%
rename from template-parts/branded-emails/email-styles.php
rename to templates/branded-emails/email-styles.php
diff --git a/template-parts/branded-emails/email-template.php b/templates/branded-emails/email-template.php
similarity index 93%
rename from template-parts/branded-emails/email-template.php
rename to templates/branded-emails/email-template.php
index d930b2c..860bb52 100644
--- a/template-parts/branded-emails/email-template.php
+++ b/templates/branded-emails/email-template.php
@@ -24,7 +24,7 @@
 	<head>
 		<meta charset="UTF-8">
 		<title><?php echo esc_attr( $email_subject ); ?></title>
-		<?php Templates::include_template_part( 'branded-emails/email-styles.php' ); ?>
+		<?php Templates::include_template( 'branded-emails/email-styles.php' ); ?>
 	</head>
 
 	<body>

From c658d3fdbdc371049ec8ede74b5e40f50bd64f65 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Tue, 5 Aug 2025 11:46:36 +0100
Subject: [PATCH 08/25] New: bring template inline with WooCommerce base

---
 templates/branded-emails/email-styles.php   | 215 ++++++++++++++++++--
 templates/branded-emails/email-template.php | 114 ++++++++---
 2 files changed, 285 insertions(+), 44 deletions(-)

diff --git a/templates/branded-emails/email-styles.php b/templates/branded-emails/email-styles.php
index bf7c4ae..6e631e1 100644
--- a/templates/branded-emails/email-styles.php
+++ b/templates/branded-emails/email-styles.php
@@ -10,45 +10,218 @@
 	exit; // Exit if accessed directly.
 }
 
-$background_color = apply_filters( 'orbit_branded_emails_background_color', '#f4f4f4' );
+$global_settings = wp_get_global_settings();
+$background_color = apply_filters( 'orbit_branded_emails_background_color', '#ffffff' );
 $body_background_color = apply_filters( 'orbit_branded_emails_body_background_color', '#ffffff' );
-$body_border_color = apply_filters( 'orbit_branded_emails_body_border_color', '#ddd' );
-$body_max_width = apply_filters( 'orbit_branded_emails_body_max_width', '800px' );
-$body_text_color = apply_filters( 'orbit_branded_emails_body_text_color', '#000' );
-$footer_text_color = apply_filters( 'orbit_branded_emails_footer_text_color', '#999' );
+$body_border_color = apply_filters( 'orbit_branded_emails_body_border_color', $global_settings['custom']['color']['border'] ?? '#EDEFF1' );
+$body_text_color = apply_filters( 'orbit_branded_emails_body_text_color', $global_settings['color']['contrast'] ?? '#3F474D' );
+$link_color = apply_filters( 'orbit_branded_emails_link_color', $global_settings['custom']['color']['link'] ?? '#8549FF' );
+$footer_text_color = apply_filters( 'orbit_branded_emails_footer_text_color', $global_settings['color']['contrast'] ?? '#3F474D' );
+$font_family = '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif';
 ?>
 
 <style>
 	body {
 		background: <?php echo esc_attr( $background_color ); ?>;
-		font-family: "Helvetica Neue", Helvetica, Roboto, Arial, sans-serif;
-		padding: 20px;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		padding: 0;
+		text-align: center;
+	}
+
+	#outer_wrapper {
+		background: <?php echo esc_attr( $background_color ); ?>;
 	}
 
-	.email-wrapper {
-		background: <?php echo esc_attr( $body_background_color ); ?>;
-		border: 1px solid <?php echo esc_attr( $body_border_color ); ?>;
+	#inner_wrapper {
+		background-color: <?php echo esc_attr( $body_background_color ); ?>;
 		border-radius: 6px;
-		color: <?php echo esc_attr( $body_text_color ); ?>;
-		max-width: <?php echo esc_attr( $body_max_width ); ?>;
+	}
+
+	#email_wrapper {
 		margin: 0 auto;
-		padding: 20px;
+		padding: 24px 0;
+		-webkit-text-size-adjust: none !important;
+		width: 100%;
+		max-width: 600px;
+	}
+
+	#template_container {
+		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+		border-radius: 3px !important;
+	}
+
+	#template_header {
+		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+		border-radius: 3px 3px 0 0 !important;
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		border-bottom: 0;
+		font-weight: bold;
+		line-height: 100%;
+		vertical-align: middle;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 	}
 
-	.email-header img {
-		max-height: 100px;
-		width: auto;
+	#template_header h1 {
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		background-color: inherit;
+	}
+
+	#template_header_image {
+		padding: 32px 32px 0;
 	}
 
-	.email-content {
-		margin-bottom: 40px;
-		margin-top: 40px;
+	#template_header_image p {
+		margin-bottom: 0;
+		text-align: left;
 	}
 
-	.email-footer {
+	#template_header_image img {
+		width: <?php echo esc_attr( $logo_image_width ); ?>px;
+	}
+
+	.email-logo-text {
+		color: <?php echo esc_attr( $link_color ); ?>;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-size: 18px;
+	}
+
+	.email-introduction {
+		padding-bottom: 24px;
+	}
+
+	#template_footer td {
+		padding: 0;
+	}
+
+	#template_footer #credit {
+		border: 0;
+		border-top: 1px solid <?php echo esc_attr( $body_border_color ); ?>;
 		color: <?php echo esc_attr( $footer_text_color ); ?>;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 12px;
-		margin-top: 20px;
+		line-height: 140%;
 		text-align: center;
+		padding: 32px;
+	}
+
+	#template_footer #credit p {
+		margin: 0;
+	}
+
+	#body_content {
+		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+	}
+
+	#body_content table td th {
+		padding: 12px;
+	}
+	#body_content p {
+		margin: 0 0 16px;
+	}
+
+	#body_content_inner {
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-size: 16px;
+		line-height: 150%;
+		text-align: left;
+	}
+
+	#body_content_inner_cell {
+		padding: 20px 32px 32px;
+	}
+
+	.td {
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		vertical-align: middle;
+	}
+
+	#header_wrapper {
+		padding: 20px 32px 0;
+		display: block;
+	}
+
+	#template_footer #credit,
+	#template_footer #credit a {
+		color: <?php echo esc_attr( $footer_text_color ); ?>;
+	}
+
+	h1 {
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-size: 32px;
+		font-weight: 700;
+		letter-spacing: -1px;
+		line-height: 120%;
+		margin: 0;
+		text-align: left;
+	}
+
+	h2 {
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		display: block;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-size: 20px;
+		font-weight: bold;
+		line-height: 160%;
+		margin: 0 0 18px;
+		text-align: left;
+	}
+
+	h3 {
+		color: <?php echo esc_attr( $body_text_color ); ?>;
+		display: block;
+		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-size: 16px;
+		font-weight: bold;
+		line-height: 160%;
+		margin: 16px 0 8px;
+		text-align: left;
+	}
+
+	a {
+		color: <?php echo esc_attr( $link_color ); ?>;
+		font-weight: normal;
+		text-decoration: underline;
+	}
+
+	img {
+		border: none;
+		display: inline-block;
+		font-size: 14px;
+		font-weight: bold;
+		height: auto;
+		outline: none;
+		text-decoration: none;
+		text-transform: capitalize;
+		vertical-align: middle;
+		margin-left: 24px;
+		max-width: 100%;
+	}
+
+	/**
+	* Media queries are not supported by all email clients, however they do work on modern mobile
+	* Gmail clients and can help us achieve better consistency there.
+	*/
+	@media screen and (max-width: 600px) {
+		#template_header_image {
+			padding: 16px 10px 0 !important;
+		}
+
+		#header_wrapper {
+			padding: 16px 10px 0 !important;
+		}
+
+		#header_wrapper h1 {
+			font-size: 24px !important;
+		}
+
+		#body_content_inner_cell {
+			padding: 10px !important;
+		}
+
+		#body_content_inner {
+			font-size: 12px !important;
+		}
 	}
 </style>
diff --git a/templates/branded-emails/email-template.php b/templates/branded-emails/email-template.php
index 860bb52..b5daeb2 100644
--- a/templates/branded-emails/email-template.php
+++ b/templates/branded-emails/email-template.php
@@ -15,37 +15,105 @@
 }
 
 $header_logo = apply_filters( 'orbit_branded_emails_header_logo', '' );
+$site_name = get_bloginfo( 'name', 'display' );
 $email_content = $args['email_content'] ?? '';
 $email_subject = $args['email_subject'] ?? get_bloginfo( 'name', 'display' );
 ?>
 
 <!DOCTYPE html>
-<html>
+<html <?php language_attributes(); ?>>
 	<head>
-		<meta charset="UTF-8">
+		<meta http-equiv="Content-Type" content="text/html; charset=<?php bloginfo( 'charset' ); ?>" />
+		<meta content="width=device-width, initial-scale=1.0" name="viewport">
 		<title><?php echo esc_attr( $email_subject ); ?></title>
 		<?php Templates::include_template( 'branded-emails/email-styles.php' ); ?>
 	</head>
-
-	<body>
-		<div class="email-wrapper">
-			<div class="email-header">
-				<?php
-				if ( ! empty( $header_logo ) ) {
-					echo '<p style="margin-top:0;"><img src="' . esc_url( $header_logo ) . '" alt="' . esc_attr( get_bloginfo( 'name', 'display' ) ) . '" /></p>';
-				} else {
-					echo '<h1>' . esc_html( get_bloginfo( 'name' ) ) . '</h1>';
-				}
-				?>
-			</div>
-
-			<div class="email-content">
-				<?php echo wp_kses_post( wpautop( $email_content ) ); ?>
-			</div>
-
-			<div class="email-footer">
-				Sent from <?php echo esc_html( get_bloginfo( 'name', 'display' ) ); ?>
-			</div>
-		</div>
+	<body marginwidth="0" topmargin="0" marginheight="0" offset="0">
+		<table width="100%" id="outer_wrapper">
+			<tr>
+				<td><!-- Deliberately empty to support consistent sizing and layout across multiple email clients. --></td>
+				<td width="600">
+					<div id="email_wrapper">
+						<table border="0" cellpadding="0" cellspacing="0" height="100%" width="100%" id="inner_wrapper">
+							<tr>
+								<td align="center" valign="top">
+									<table border="0" cellpadding="0" cellspacing="0" width="100%">
+										<tr>
+											<td id="template_header_image">
+												<?php
+												if ( $header_logo ) {
+													echo '<p style="margin-top:0;"><img src="' . esc_url( $header_logo ) . '" alt="' . esc_attr( $site_name ) . '" /></p>';
+												} else {
+													echo '<p class="email-logo-text">' . esc_html( $site_name ) . '</p>';
+												}
+												?>
+											</td>
+										</tr>
+									</table>
+									<table border="0" cellpadding="0" cellspacing="0" width="100%" id="template_container">
+										<tr>
+											<td align="center" valign="top">
+												<!-- Header -->
+												<table border="0" cellpadding="0" cellspacing="0" width="100%" id="template_header">
+													<tr>
+														<td id="header_wrapper">
+															<h1><?php echo esc_html( $email_subject ); ?></h1>
+														</td>
+													</tr>
+												</table>
+												<!-- End Header -->
+											</td>
+										</tr>
+										<tr>
+											<td align="center" valign="top">
+												<!-- Body -->
+												<table border="0" cellpadding="0" cellspacing="0" width="100%" id="template_body">
+													<tr>
+														<td valign="top" id="body_content">
+															<!-- Content -->
+															<table border="0" cellpadding="20" cellspacing="0" width="100%">
+																<tr>
+																	<td valign="top" id="body_content_inner_cell">
+																		<div id="body_content_inner">
+																			<?php echo wp_kses_post( wpautop( $email_content ) ); ?>
+																		</div>
+																	</td>
+																</tr>
+															</table>
+															<!-- End Content -->
+														</td>
+													</tr>
+												</table>
+												<!-- End Body -->
+											</td>
+										</tr>
+									</table>
+								</td>
+							</tr>
+							<tr>
+								<td align="center" valign="top">
+									<!-- Footer -->
+									<table border="0" cellpadding="10" cellspacing="0" width="100%" id="template_footer">
+										<tr>
+											<td valign="top">
+												<table border="0" cellpadding="10" cellspacing="0" width="100%">
+													<tr>
+														<td colspan="2" valign="middle" id="credit">
+															<p>Sent from <?php echo esc_html( get_bloginfo( 'name', 'display' ) ); ?></p>
+														</td>
+													</tr>
+												</table>
+											</td>
+										</tr>
+									</table>
+									<!-- End Footer -->
+								</td>
+							</tr>
+						</table>
+					</div>
+				</td>
+				<td><!-- Deliberately empty to support consistent sizing and layout across multiple email clients. --></td>
+			</tr>
+		</table>
 	</body>
 </html>

From 4efc8a3d32184a22c3c17b8189cc5cb08ee1dd87 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Thu, 7 Aug 2025 12:30:11 +0100
Subject: [PATCH 09/25] New: inline all the styles from within <style> before
 passing email content back

---
 composer.json                             |  3 +-
 includes/classes/BrandedEmails.php        | 50 ++++++++++++++++-------
 orbit.php                                 |  1 +
 templates/branded-emails/email-styles.php |  1 +
 4 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/composer.json b/composer.json
index 0e81aa0..cee258a 100644
--- a/composer.json
+++ b/composer.json
@@ -5,7 +5,8 @@
 	"license": "MIT",
 	"minimum-stability": "stable",
 	"require": {
-		"php": ">=8.0"
+		"php": ">=8.0",
+		"pelago/emogrifier": "^8.0"
 	},
 	"autoload": {
 		"psr-4": {
diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 0c3380e..12c7e18 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -7,6 +7,8 @@
 
 namespace Eighteen73\Orbit;
 
+use Exception;
+use Pelago\Emogrifier\CssInliner;
 /**
  * This class is built upon BE Media from Production so all due credit to those authors.
  * http://www.github.com/billerickson/be-media-from-production
@@ -62,6 +64,17 @@ public function apply_branded_email_template( $args ) {
 			return $args;
 		}
 
+		// Remove existing Content-Type headers (at this point we've already established it's not HTML)
+		$headers = array_filter(
+			$headers,
+			function ( $header ) {
+				return stripos( $header, 'Content-Type:' ) === false;
+			}
+		);
+
+		// Add HTML Content-Type
+		$headers[] = 'Content-Type: text/html; charset=UTF-8';
+
 		ob_start();
 
 		Templates::include_template(
@@ -72,22 +85,13 @@ public function apply_branded_email_template( $args ) {
 			]
 		);
 
-		$styled_message = ob_get_clean();
+		$raw_email_content = ob_get_clean();
 
-		// Remove existing Content-Type headers (at this point we've already established it's not HTML)
-		$headers = array_filter(
-			$headers,
-			function ( $header ) {
-				return stripos( $header, 'Content-Type:' ) === false;
-			}
-		);
-
-		// Add HTML Content-Type
-		$headers[] = 'Content-Type: text/html; charset=UTF-8';
+		$email_content = $this->style_inline( $raw_email_content );
 
 		// Set updated headers and message
 		$args['headers'] = $headers;
-		$args['message'] = $styled_message;
+		$args['message'] = $email_content;
 
 		return $args;
 	}
@@ -112,8 +116,26 @@ public function apply_branded_email_template_to_gf_notifications( $template ) {
 			]
 		);
 
-		$template = ob_get_clean();
+		$raw_email_content = ob_get_clean();
+
+		$email_content = $this->style_inline( $raw_email_content );
+
+		return $email_content;
+	}
+
+	/**
+	 * Apply inline styles to email content.
+	 *
+	 * @param string|null $email_content Content that will receive inline styles.
+	 * @return string The email content with inline styles applied.
+	 */
+	public function style_inline( $email_content ) {
+		try {
+			$inlined_content = CssInliner::fromHtml( $email_content )->inlineCss()->render();
+		} catch ( Exception $e ) {
+			$inlined_content = $email_content;
+		}
 
-		return $template;
+		return $inlined_content;
 	}
 }
diff --git a/orbit.php b/orbit.php
index 0dbcbea..9033fcb 100644
--- a/orbit.php
+++ b/orbit.php
@@ -25,6 +25,7 @@
 define( 'ORBIT_PATH', plugin_dir_path( __FILE__ ) );
 define( 'ORBIT_INC', ORBIT_PATH . 'includes/' );
 
+require_once ORBIT_PATH . '/vendor/autoload.php';
 require_once 'autoload.php';
 
 DisallowIndexing\DisallowIndexing::instance()->setup();
diff --git a/templates/branded-emails/email-styles.php b/templates/branded-emails/email-styles.php
index 6e631e1..a9356bc 100644
--- a/templates/branded-emails/email-styles.php
+++ b/templates/branded-emails/email-styles.php
@@ -18,6 +18,7 @@
 $link_color = apply_filters( 'orbit_branded_emails_link_color', $global_settings['custom']['color']['link'] ?? '#8549FF' );
 $footer_text_color = apply_filters( 'orbit_branded_emails_footer_text_color', $global_settings['color']['contrast'] ?? '#3F474D' );
 $font_family = '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif';
+$logo_image_width = apply_filters( 'orbit_branded_emails_logo_image_width', 200 );
 ?>
 
 <style>

From 63d34a6578164de9c1ac06186eaf1eb3931f8415 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Thu, 7 Aug 2025 13:41:42 +0100
Subject: [PATCH 10/25] New: use mozart to handle dependency loading

---
 autoload.php                                  |    1 +
 composer.json                                 |   22 +-
 .../Emogrifier/Caching/SimpleStringCache.php  |   87 ++
 .../Pelago/Emogrifier/Css/CssDocument.php     |  202 +++
 .../Pelago/Emogrifier/Css/StyleRule.php       |   91 ++
 .../Pelago/Emogrifier/CssInliner.php          | 1211 +++++++++++++++++
 .../HtmlProcessor/AbstractHtmlProcessor.php   |  478 +++++++
 .../HtmlProcessor/CssToAttributeConverter.php |  261 ++++
 .../HtmlProcessor/CssVariableEvaluator.php    |  200 +++
 .../HtmlProcessor/HtmlNormalizer.php          |   14 +
 .../Emogrifier/HtmlProcessor/HtmlPruner.php   |  141 ++
 .../Emogrifier/Utilities/ArrayIntersector.php |   57 +
 .../Emogrifier/Utilities/CssConcatenator.php  |  181 +++
 .../Utilities/DeclarationBlockParser.php      |   96 ++
 .../Pelago/Emogrifier/Utilities/Preg.php      |  202 +++
 .../Sabberworm/CSS/CSSElement.php             |   17 +
 .../CSS/CSSList/AtRuleBlockList.php           |   72 +
 .../Sabberworm/CSS/CSSList/CSSBlockList.php   |  184 +++
 .../Sabberworm/CSS/CSSList/CSSList.php        |  428 ++++++
 .../Sabberworm/CSS/CSSList/CSSListItem.php    |   18 +
 .../Sabberworm/CSS/CSSList/Document.php       |   65 +
 .../Sabberworm/CSS/CSSList/KeyFrame.php       |   87 ++
 .../Sabberworm/CSS/Comment/Comment.php        |   49 +
 .../CSS/Comment/CommentContainer.php          |   44 +
 .../Sabberworm/CSS/Comment/Commentable.php    |   26 +
 .../Sabberworm/CSS/OutputFormat.php           |  753 ++++++++++
 .../Sabberworm/CSS/OutputFormatter.php        |  235 ++++
 .../Dependencies/Sabberworm/CSS/Parser.php    |   42 +
 .../Sabberworm/CSS/Parsing/Anchor.php         |   35 +
 .../CSS/Parsing/OutputException.php           |   10 +
 .../Sabberworm/CSS/Parsing/ParserState.php    |  464 +++++++
 .../CSS/Parsing/SourceException.php           |   25 +
 .../CSS/Parsing/UnexpectedEOFException.php    |   12 +
 .../CSS/Parsing/UnexpectedTokenException.php  |   31 +
 .../Sabberworm/CSS/Position/Position.php      |   55 +
 .../Sabberworm/CSS/Position/Positionable.php  |   31 +
 .../Sabberworm/CSS/Property/AtRule.php        |   29 +
 .../Sabberworm/CSS/Property/CSSNamespace.php  |   97 ++
 .../Sabberworm/CSS/Property/Charset.php       |   74 +
 .../Sabberworm/CSS/Property/Import.php        |   85 ++
 .../CSS/Property/KeyframeSelector.php         |   27 +
 .../Sabberworm/CSS/Property/Selector.php      |   77 ++
 .../Selector/SpecificityCalculator.php        |   85 ++
 .../Sabberworm/CSS/Renderable.php             |   10 +
 .../Dependencies/Sabberworm/CSS/Rule/Rule.php |  198 +++
 .../Sabberworm/CSS/RuleSet/AtRuleSet.php      |   68 +
 .../CSS/RuleSet/DeclarationBlock.php          |  301 ++++
 .../Sabberworm/CSS/RuleSet/RuleContainer.php  |   36 +
 .../Sabberworm/CSS/RuleSet/RuleSet.php        |  375 +++++
 .../Dependencies/Sabberworm/CSS/Settings.php  |  124 ++
 .../Sabberworm/CSS/Value/CSSFunction.php      |  116 ++
 .../Sabberworm/CSS/Value/CSSString.php        |   95 ++
 .../Sabberworm/CSS/Value/CalcFunction.php     |  105 ++
 .../CSS/Value/CalcRuleValueList.php           |   23 +
 .../Sabberworm/CSS/Value/Color.php            |  390 ++++++
 .../Sabberworm/CSS/Value/LineName.php         |   59 +
 .../Sabberworm/CSS/Value/PrimitiveValue.php   |    7 +
 .../Sabberworm/CSS/Value/RuleValueList.php    |   22 +
 .../Sabberworm/CSS/Value/Size.php             |  210 +++
 .../Dependencies/Sabberworm/CSS/Value/URL.php |   83 ++
 .../Sabberworm/CSS/Value/Value.php            |  211 +++
 .../Sabberworm/CSS/Value/ValueList.php        |   96 ++
 .../Component/CssSelector/CHANGELOG.md        |   29 +
 .../CssSelector/CssSelectorConverter.php      |   67 +
 .../Exception/ExceptionInterface.php          |   24 +
 .../Exception/ExpressionErrorException.php    |   24 +
 .../Exception/InternalErrorException.php      |   24 +
 .../CssSelector/Exception/ParseException.php  |   24 +
 .../Exception/SyntaxErrorException.php        |   55 +
 .../Symfony/Component/CssSelector/LICENSE     |   19 +
 .../CssSelector/Node/AbstractNode.php         |   32 +
 .../CssSelector/Node/AttributeNode.php        |   73 +
 .../Component/CssSelector/Node/ClassNode.php  |   51 +
 .../CssSelector/Node/CombinedSelectorNode.php |   59 +
 .../CssSelector/Node/ElementNode.php          |   53 +
 .../CssSelector/Node/FunctionNode.php         |   70 +
 .../Component/CssSelector/Node/HashNode.php   |   51 +
 .../CssSelector/Node/MatchingNode.php         |   55 +
 .../CssSelector/Node/NegationNode.php         |   51 +
 .../CssSelector/Node/NodeInterface.php        |   29 +
 .../Component/CssSelector/Node/PseudoNode.php |   54 +
 .../CssSelector/Node/SelectorNode.php         |   54 +
 .../CssSelector/Node/Specificity.php          |   69 +
 .../Node/SpecificityAdjustmentNode.php        |   49 +
 .../Parser/Handler/CommentHandler.php         |   45 +
 .../Parser/Handler/HandlerInterface.php       |   30 +
 .../Parser/Handler/HashHandler.php            |   52 +
 .../Parser/Handler/IdentifierHandler.php      |   52 +
 .../Parser/Handler/NumberHandler.php          |   49 +
 .../Parser/Handler/StringHandler.php          |   71 +
 .../Parser/Handler/WhitespaceHandler.php      |   43 +
 .../Component/CssSelector/Parser/Parser.php   |  385 ++++++
 .../CssSelector/Parser/ParserInterface.php    |   34 +
 .../Component/CssSelector/Parser/Reader.php   |   82 ++
 .../Parser/Shortcut/ClassParser.php           |   48 +
 .../Parser/Shortcut/ElementParser.php         |   44 +
 .../Parser/Shortcut/EmptyStringParser.php     |   43 +
 .../Parser/Shortcut/HashParser.php            |   48 +
 .../Component/CssSelector/Parser/Token.php    |  107 ++
 .../CssSelector/Parser/TokenStream.php        |  156 +++
 .../Parser/Tokenizer/Tokenizer.php            |   73 +
 .../Parser/Tokenizer/TokenizerEscaping.php    |   63 +
 .../Parser/Tokenizer/TokenizerPatterns.php    |   89 ++
 .../Symfony/Component/CssSelector/README.md   |   20 +
 .../XPath/Extension/AbstractExtension.php     |   50 +
 .../Extension/AttributeMatchingExtension.php  |  113 ++
 .../XPath/Extension/CombinationExtension.php  |   65 +
 .../XPath/Extension/ExtensionInterface.php    |   67 +
 .../XPath/Extension/FunctionExtension.php     |  165 +++
 .../XPath/Extension/HtmlExtension.php         |  178 +++
 .../XPath/Extension/NodeExtension.php         |  221 +++
 .../XPath/Extension/PseudoClassExtension.php  |  122 ++
 .../CssSelector/XPath/Translator.php          |  224 +++
 .../CssSelector/XPath/TranslatorInterface.php |   37 +
 .../Component/CssSelector/XPath/XPathExpr.php |  107 ++
 .../Component/CssSelector/composer.json       |   32 +
 includes/classes/BrandedEmails.php            |    3 +-
 orbit.php                                     |    1 -
 118 files changed, 12862 insertions(+), 3 deletions(-)
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Caching/SimpleStringCache.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Css/CssDocument.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Css/StyleRule.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/CssInliner.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/AbstractHtmlProcessor.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssToAttributeConverter.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssVariableEvaluator.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlNormalizer.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlPruner.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Utilities/ArrayIntersector.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Utilities/CssConcatenator.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Utilities/DeclarationBlockParser.php
 create mode 100644 includes/Dependencies/Pelago/Emogrifier/Utilities/Preg.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSElement.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSList/AtRuleBlockList.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSList/CSSBlockList.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSList/CSSList.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSList/CSSListItem.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSList/Document.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/CSSList/KeyFrame.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Comment/Comment.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Comment/CommentContainer.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Comment/Commentable.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/OutputFormat.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/OutputFormatter.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parser.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parsing/Anchor.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parsing/OutputException.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parsing/ParserState.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parsing/SourceException.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedEOFException.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedTokenException.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Position/Position.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Position/Positionable.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/AtRule.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/CSSNamespace.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/Charset.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/Import.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/KeyframeSelector.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/Selector.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Property/Selector/SpecificityCalculator.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Renderable.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Rule/Rule.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/RuleSet/AtRuleSet.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/RuleSet/DeclarationBlock.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/RuleSet/RuleContainer.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/RuleSet/RuleSet.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Settings.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/CSSFunction.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/CSSString.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/CalcFunction.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/CalcRuleValueList.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/Color.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/LineName.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/PrimitiveValue.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/RuleValueList.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/Size.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/URL.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/Value.php
 create mode 100644 includes/Dependencies/Sabberworm/CSS/Value/ValueList.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/CHANGELOG.md
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/CssSelectorConverter.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Exception/ExceptionInterface.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Exception/ExpressionErrorException.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Exception/InternalErrorException.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Exception/ParseException.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Exception/SyntaxErrorException.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/LICENSE
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/AbstractNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/AttributeNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/ClassNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/CombinedSelectorNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/ElementNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/FunctionNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/HashNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/MatchingNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/NegationNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/NodeInterface.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/PseudoNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/SelectorNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/Specificity.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Node/SpecificityAdjustmentNode.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/CommentHandler.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HandlerInterface.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HashHandler.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/IdentifierHandler.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/NumberHandler.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/StringHandler.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/WhitespaceHandler.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Parser.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/ParserInterface.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Reader.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ClassParser.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ElementParser.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/EmptyStringParser.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/HashParser.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Token.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/TokenStream.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/Tokenizer.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerEscaping.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerPatterns.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/README.md
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AbstractExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AttributeMatchingExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/CombinationExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/ExtensionInterface.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/FunctionExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/HtmlExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/NodeExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/PseudoClassExtension.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/Translator.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/TranslatorInterface.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/XPath/XPathExpr.php
 create mode 100644 includes/Dependencies/Symfony/Component/CssSelector/composer.json

diff --git a/autoload.php b/autoload.php
index 51ef338..dc6f098 100644
--- a/autoload.php
+++ b/autoload.php
@@ -16,6 +16,7 @@
 	function ( $class ) {
 		$namspaces = [
 			'Eighteen73\\Orbit\\' => __DIR__ . '/includes/classes/',
+			'Eighteen73\\Orbit\\Dependencies\\' => __DIR__ . '/includes/dependencies/',
 		];
 		foreach ( $namspaces as $prefix => $base_dir ) {
 			$len = strlen( $prefix );
diff --git a/composer.json b/composer.json
index cee258a..0cf1cf3 100644
--- a/composer.json
+++ b/composer.json
@@ -19,11 +19,31 @@
 		}
 	},
 	"require-dev": {
-		"eighteen73/wordpress-coding-standards": "^2.0.0"
+		"eighteen73/wordpress-coding-standards": "^2.0.0",
+		"coenjacobs/mozart": "^0.7.1"
 	},
+  "extra": {
+    "mozart": {
+        "dep_namespace": "Eighteen73\\Orbit\\Dependencies\\",
+        "dep_directory": "/includes/Dependencies/",
+        "classmap_directory": "/includes/classes/dependencies/",
+        "classmap_prefix": "Eighteen73_Orbit_",
+        "packages": [
+            "pelago/emogrifier"
+        ]
+    }
+  },
   "scripts": {
     "test": [
       "phpcs"
+    ],
+    "post-install-cmd": [
+        "\"vendor/bin/mozart\" compose",
+        "composer dump-autoload"
+    ],
+    "post-update-cmd": [
+        "\"vendor/bin/mozart\" compose",
+        "composer dump-autoload"
     ]
   }
 }
diff --git a/includes/Dependencies/Pelago/Emogrifier/Caching/SimpleStringCache.php b/includes/Dependencies/Pelago/Emogrifier/Caching/SimpleStringCache.php
new file mode 100644
index 0000000..97125a7
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Caching/SimpleStringCache.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Caching;
+
+/**
+ * This cache caches string values with string keys. It is not PSR-6-compliant.
+ *
+ * Usage:
+ *
+ * ```php
+ * $cache = new SimpleStringCache();
+ * $cache->set($key, $value);
+ * …
+ * if ($cache->has($key) {
+ *     $cachedValue = $cache->get($value);
+ * }
+ * ```
+ *
+ * @internal
+ */
+final class SimpleStringCache
+{
+    /**
+     * @var array<string, string>
+     */
+    private $values = [];
+
+    /**
+     * Checks whether there is an entry stored for the given key.
+     *
+     * @param string $key the key to check; must not be empty
+     *
+     * @throws \InvalidArgumentException
+     */
+    public function has(string $key): bool
+    {
+        $this->assertNotEmptyKey($key);
+
+        return isset($this->values[$key]);
+    }
+
+    /**
+     * Returns the entry stored for the given key, and throws an exception if the value does not exist
+     * (which helps keep the return type simple).
+     *
+     * @param string $key the key to of the item to retrieve; must not be empty
+     *
+     * @return string the retrieved value; may be empty
+     *
+     * @throws \BadMethodCallException
+     */
+    public function get(string $key): string
+    {
+        if (!$this->has($key)) {
+            throw new \BadMethodCallException('You can only call `get` with a key for an existing value.', 1625996246);
+        }
+
+        return $this->values[$key];
+    }
+
+    /**
+     * Sets or overwrites an entry.
+     *
+     * @param string $key the key to of the item to set; must not be empty
+     * @param string $value the value to set; can be empty
+     *
+     * @throws \BadMethodCallException
+     */
+    public function set(string $key, string $value): void
+    {
+        $this->assertNotEmptyKey($key);
+
+        $this->values[$key] = $value;
+    }
+
+    /**
+     * @throws \InvalidArgumentException
+     */
+    private function assertNotEmptyKey(string $key): void
+    {
+        if ($key === '') {
+            throw new \InvalidArgumentException('Please provide a non-empty key.', 1625995840);
+        }
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/Css/CssDocument.php b/includes/Dependencies/Pelago/Emogrifier/Css/CssDocument.php
new file mode 100644
index 0000000..27d8d1d
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Css/CssDocument.php
@@ -0,0 +1,202 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Css;
+
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\Preg;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\AtRuleBlockList as CssAtRuleBlockList;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\Document as SabberwormCssDocument;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parser as CssParser;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\AtRule as CssAtRule;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Charset as CssCharset;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Import as CssImport;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Renderable as CssRenderable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\DeclarationBlock as CssDeclarationBlock;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\RuleSet as CssRuleSet;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Settings as ParserSettings;
+
+/**
+ * Parses and stores a CSS document from a string of CSS, and provides methods to obtain the CSS in parts or as data
+ * structures.
+ *
+ * @internal
+ */
+final class CssDocument
+{
+    /**
+     * @var SabberwormCssDocument
+     */
+    private $sabberwormCssDocument;
+
+    /**
+     * `@import` rules must precede all other types of rules, except `@charset` rules.  This property is used while
+     * rendering at-rules to enforce that.
+     *
+     * @var bool
+     */
+    private $isImportRuleAllowed = true;
+
+    /**
+     * @param string $css
+     * @param bool $debug
+     *        If this is `true`, an exception will be thrown if invalid CSS is encountered.
+     *        Otherwise the parser will try to do the best it can.
+     */
+    public function __construct(string $css, bool $debug)
+    {
+        // CSS Parser currently throws exception with nested at-rules (like `@media`) in strict parsing mode
+        $parserSettings = ParserSettings::create()->withLenientParsing(!$debug || $this->hasNestedAtRule($css));
+
+        // CSS Parser currently throws exception with non-empty whitespace-only CSS in strict parsing mode, so `trim()`
+        // @see https://github.com/sabberworm/PHP-CSS-Parser/issues/349
+        $this->sabberwormCssDocument = (new CssParser(\trim($css), $parserSettings))->parse();
+    }
+
+    /**
+     * Tests if a string of CSS appears to contain an at-rule with nested rules
+     * (`@media`, `@supports`, `@keyframes`, `@document`,
+     * the latter two additionally with vendor prefixes that may commonly be used).
+     *
+     * @see https://github.com/sabberworm/PHP-CSS-Parser/issues/127
+     */
+    private function hasNestedAtRule(string $css): bool
+    {
+        return (new Preg())
+                ->match('/@(?:media|supports|(?:-webkit-|-moz-|-ms-|-o-)?+(keyframes|document))\\b/', $css) !== 0;
+    }
+
+    /**
+     * Collates the media query, selectors and declarations for individual rules from the parsed CSS, in order.
+     *
+     * @param array<array-key, string> $allowedMediaTypes
+     *
+     * @return list<StyleRule>
+     */
+    public function getStyleRulesData(array $allowedMediaTypes): array
+    {
+        $ruleMatches = [];
+        foreach ($this->sabberwormCssDocument->getContents() as $rule) {
+            if ($rule instanceof CssAtRuleBlockList) {
+                $containingAtRule = $this->getFilteredAtIdentifierAndRule($rule, $allowedMediaTypes);
+                if (\is_string($containingAtRule)) {
+                    foreach ($rule->getContents() as $nestedRule) {
+                        if ($nestedRule instanceof CssDeclarationBlock) {
+                            $ruleMatches[] = new StyleRule($nestedRule, $containingAtRule);
+                        }
+                    }
+                }
+            } elseif ($rule instanceof CssDeclarationBlock) {
+                $ruleMatches[] = new StyleRule($rule);
+            }
+        }
+
+        return $ruleMatches;
+    }
+
+    /**
+     * Renders at-rules from the parsed CSS that are valid and not conditional group rules (i.e. not rules such as
+     * `@media` which contain style rules whose data is returned by {@see getStyleRulesData}).  Also does not render
+     * `@charset` rules; these are discarded (only UTF-8 is supported).
+     *
+     * @return string
+     */
+    public function renderNonConditionalAtRules(): string
+    {
+        $this->isImportRuleAllowed = true;
+        $cssContents = $this->sabberwormCssDocument->getContents();
+        $atRules = \array_filter($cssContents, [$this, 'isValidAtRuleToRender']);
+
+        if ($atRules === []) {
+            return '';
+        }
+
+        $atRulesDocument = new SabberwormCssDocument();
+        $atRulesDocument->setContents($atRules);
+
+        return $atRulesDocument->render();
+    }
+
+    /**
+     * @param CssAtRuleBlockList $rule
+     * @param array<array-key, string> $allowedMediaTypes
+     *
+     * @return ?string
+     *         If the nested at-rule is supported, it's opening declaration (e.g. "@media (max-width: 768px)") is
+     *         returned; otherwise the return value is null.
+     */
+    private function getFilteredAtIdentifierAndRule(CssAtRuleBlockList $rule, array $allowedMediaTypes): ?string
+    {
+        $result = null;
+
+        if ($rule->atRuleName() === 'media') {
+            $mediaQueryList = $rule->atRuleArgs();
+            [$mediaType] = \explode('(', $mediaQueryList, 2);
+            if (\trim($mediaType) !== '') {
+                $escapedAllowedMediaTypes = \array_map(
+                    static function (string $allowedMediaType): string {
+                        return \preg_quote($allowedMediaType, '/');
+                    },
+                    $allowedMediaTypes
+                );
+                $mediaTypesMatcher = \implode('|', $escapedAllowedMediaTypes);
+                $isAllowed
+                    = (new Preg())->match('/^\\s*+(?:only\\s++)?+(?:' . $mediaTypesMatcher . ')/i', $mediaType) !== 0;
+            } else {
+                $isAllowed = true;
+            }
+
+            if ($isAllowed) {
+                $result = '@media ' . $mediaQueryList;
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * Tests if a CSS rule is an at-rule that should be passed though and copied to a `<style>` element unmodified:
+     * - `@charset` rules are discarded - only UTF-8 is supported - `false` is returned;
+     * - `@import` rules are passed through only if they satisfy the specification ("user agents must ignore any
+     *   '@import' rule that occurs inside a block or after any non-ignored statement other than an '@charset' or an
+     *   '@import' rule");
+     * - `@media` rules are processed separately to see if their nested rules apply - `false` is returned;
+     * - `@font-face` rules are checked for validity - they must contain both a `src` and `font-family` property;
+     * - other at-rules are assumed to be valid and treated as a black box - `true` is returned.
+     *
+     * @param CssRenderable $rule
+     *
+     * @return bool
+     */
+    private function isValidAtRuleToRender(CssRenderable $rule): bool
+    {
+        if ($rule instanceof CssCharset) {
+            return false;
+        }
+
+        if ($rule instanceof CssImport) {
+            return $this->isImportRuleAllowed;
+        }
+
+        $this->isImportRuleAllowed = false;
+
+        if (!$rule instanceof CssAtRule) {
+            return false;
+        }
+
+        switch ($rule->atRuleName()) {
+            case 'media':
+                $result = false;
+                break;
+            case 'font-face':
+                $result = $rule instanceof CssRuleSet
+                    && $rule->getRules('font-family') !== []
+                    && $rule->getRules('src') !== [];
+                break;
+            default:
+                $result = true;
+        }
+
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/Css/StyleRule.php b/includes/Dependencies/Pelago/Emogrifier/Css/StyleRule.php
new file mode 100644
index 0000000..09a2d87
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Css/StyleRule.php
@@ -0,0 +1,91 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Css;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\DeclarationBlock;
+
+/**
+ * This class represents a CSS style rule, including selectors, a declaration block, and an optional containing at-rule.
+ *
+ * @internal
+ */
+final class StyleRule
+{
+    /**
+     * @var DeclarationBlock
+     */
+    private $declarationBlock;
+
+    /**
+     * @var string
+     */
+    private $containingAtRule;
+
+    /**
+     * @param DeclarationBlock $declarationBlock
+     * @param string $containingAtRule e.g. `@media screen and (max-width: 480px)`
+     */
+    public function __construct(DeclarationBlock $declarationBlock, string $containingAtRule = '')
+    {
+        $this->declarationBlock = $declarationBlock;
+        $this->containingAtRule = \trim($containingAtRule);
+    }
+
+    /**
+     * @return array<int, string> the selectors, e.g. `["h1", "p"]`
+     */
+    public function getSelectors(): array
+    {
+        /** @var array<int, Selector> $selectors */
+        $selectors = $this->declarationBlock->getSelectors();
+        return \array_map(
+            static function (Selector $selector): string {
+                return $selector->getSelector();
+            },
+            $selectors
+        );
+    }
+
+    /**
+     * @return string the CSS declarations, separated and followed by a semicolon, e.g., `color: red; height: 4px;`
+     */
+    public function getDeclarationAsText(): string
+    {
+        $rules = $this->declarationBlock->getRules();
+        $renderedRules = [];
+        $outputFormat = OutputFormat::create();
+        foreach ($rules as $rule) {
+            $renderedRules[] = $rule->render($outputFormat);
+        }
+
+        return \implode(' ', $renderedRules);
+    }
+
+    /**
+     * Checks whether the declaration block has at least one declaration.
+     */
+    public function hasAtLeastOneDeclaration(): bool
+    {
+        return $this->declarationBlock->getRules() !== [];
+    }
+
+    /**
+     * @returns string e.g. `@media screen and (max-width: 480px)`, or an empty string
+     */
+    public function getContainingAtRule(): string
+    {
+        return $this->containingAtRule;
+    }
+
+    /**
+     * Checks whether the containing at-rule is non-empty and has any non-whitespace characters.
+     */
+    public function hasContainingAtRule(): bool
+    {
+        return $this->getContainingAtRule() !== '';
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/CssInliner.php b/includes/Dependencies/Pelago/Emogrifier/CssInliner.php
new file mode 100644
index 0000000..4a9623c
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/CssInliner.php
@@ -0,0 +1,1211 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier;
+
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Css\CssDocument;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\HtmlProcessor\AbstractHtmlProcessor;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\CssConcatenator;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\DeclarationBlockParser;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\Preg;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\CssSelectorConverter;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\ParseException;
+
+/**
+ * This class provides functions for converting CSS styles into inline style attributes in your HTML code.
+ */
+final class CssInliner extends AbstractHtmlProcessor
+{
+    /**
+     * @var int
+     */
+    private const CACHE_KEY_SELECTOR = 0;
+
+    /**
+     * @var int
+     */
+    private const CACHE_KEY_COMBINED_STYLES = 1;
+
+    /**
+     * Regular expression component matching a static pseudo class in a selector, without the preceding ":",
+     * for which the applicable elements can be determined (by converting the selector to an XPath expression).
+     * (Contains alternation without a group and is intended to be placed within a capturing, non-capturing or lookahead
+     * group, as appropriate for the usage context.)
+     *
+     * @var string
+     */
+    private const PSEUDO_CLASS_MATCHER
+        = 'empty|(?:first|last|nth(?:-last)?+|only)-(?:child|of-type)|not\\([[:ascii:]]*\\)|root';
+
+    /**
+     * This regular expression componenet matches an `...of-type` pseudo class name, without the preceding ":".  These
+     * pseudo-classes can currently online be inlined if they have an associated type in the selector expression.
+     *
+     * @var string
+     */
+    private const OF_TYPE_PSEUDO_CLASS_MATCHER = '(?:first|last|nth(?:-last)?+|only)-of-type';
+
+    /**
+     * regular expression component to match a selector combinator
+     *
+     * @var string
+     */
+    private const COMBINATOR_MATCHER = '(?:\\s++|\\s*+[>+~]\\s*+)(?=[[:alpha:]_\\-.#*:\\[])';
+
+    /**
+     * options array key for `querySelectorAll`
+     *
+     * @var string
+     */
+    private const QSA_ALWAYS_THROW_PARSE_EXCEPTION = 'alwaysThrowParseException';
+
+    /**
+     * @var array<string, bool>
+     */
+    private $excludedSelectors = [];
+
+    /**
+     * @var array<non-empty-string, bool>
+     */
+    private $excludedCssSelectors = [];
+
+    /**
+     * @var array<string, bool>
+     */
+    private $allowedMediaTypes = ['all' => true, 'screen' => true, 'print' => true];
+
+    /**
+     * @var array{
+     *         0: array<string, int>,
+     *         1: array<string, string>
+     *      }
+     */
+    private $caches = [
+        self::CACHE_KEY_SELECTOR => [],
+        self::CACHE_KEY_COMBINED_STYLES => [],
+    ];
+
+    /**
+     * @var ?CssSelectorConverter
+     */
+    private $cssSelectorConverter = null;
+
+    /**
+     * the visited nodes with the XPath paths as array keys
+     *
+     * @var array<string, \DOMElement>
+     */
+    private $visitedNodes = [];
+
+    /**
+     * the styles to apply to the nodes with the XPath paths as array keys for the outer array
+     * and the attribute names/values as key/value pairs for the inner array
+     *
+     * @var array<string, array<string, string>>
+     */
+    private $styleAttributesForNodes = [];
+
+    /**
+     * Determines whether the "style" attributes of tags in the the HTML passed to this class should be preserved.
+     * If set to false, the value of the style attributes will be discarded.
+     *
+     * @var bool
+     */
+    private $isInlineStyleAttributesParsingEnabled = true;
+
+    /**
+     * Determines whether the `<style>` blocks in the HTML passed to this class should be parsed.
+     *
+     * If set to true, the `<style>` blocks will be removed from the HTML and their contents will be applied to the HTML
+     * via inline styles.
+     *
+     * If set to false, the `<style>` blocks will be left as they are in the HTML.
+     *
+     * @var bool
+     */
+    private $isStyleBlocksParsingEnabled = true;
+
+    /**
+     * For calculating selector precedence order.
+     * Keys are a regular expression part to match before a CSS name.
+     * Values are a multiplier factor per match to weight specificity.
+     *
+     * @var array<string, int>
+     */
+    private $selectorPrecedenceMatchers = [
+        // IDs: worth 10000
+        '\\#' => 10000,
+        // classes, attributes, pseudo-classes (not pseudo-elements) except `:not`: worth 100
+        '(?:\\.|\\[|(?<!:):(?!not\\())' => 100,
+        // elements (not attribute values or `:not`), pseudo-elements: worth 1
+        '(?:(?<![="\':\\w\\-])|::)' => 1,
+    ];
+
+    /**
+     * array of data describing CSS rules which apply to the document but cannot be inlined, in the format returned by
+     * {@see collateCssRules}
+     *
+     * @var array<array-key, array{
+     *          media: string,
+     *          selector: string,
+     *          hasUnmatchablePseudo: bool,
+     *          declarationsBlock: string,
+     *          line: int
+     *      }>|null
+     */
+    private $matchingUninlinableCssRules = null;
+
+    /**
+     * Emogrifier will throw Exceptions when it encounters an error instead of silently ignoring them.
+     *
+     * @var bool
+     */
+    private $debug = false;
+
+    /**
+     * Inlines the given CSS into the existing HTML.
+     *
+     * @param string $css the CSS to inline, must be UTF-8-encoded
+     *
+     * @return $this
+     *
+     * @throws ParseException in debug mode, if an invalid selector is encountered
+     * @throws \RuntimeException
+     *         in debug mode, if an internal PCRE error occurs
+     *         or `CssSelectorConverter::toXPath` returns an invalid XPath expression
+     * @throws \UnexpectedValueException
+     *         if a selector query result includes a node which is not a `DOMElement`
+     */
+    public function inlineCss(string $css = ''): self
+    {
+        $this->clearAllCaches();
+        $this->purgeVisitedNodes();
+
+        $this->normalizeStyleAttributesOfAllNodes();
+
+        $combinedCss = $css;
+        // grab any existing style blocks from the HTML and append them to the existing CSS
+        // (these blocks should be appended so as to have precedence over conflicting styles in the existing CSS)
+        if ($this->isStyleBlocksParsingEnabled) {
+            $combinedCss .= $this->getCssFromAllStyleNodes();
+        }
+        $parsedCss = new CssDocument($combinedCss, $this->debug);
+
+        $excludedNodes = $this->getNodesToExclude();
+        $cssRules = $this->collateCssRules($parsedCss);
+        foreach ($cssRules['inlinable'] as $cssRule) {
+            foreach ($this->querySelectorAll($cssRule['selector']) as $node) {
+                if (\in_array($node, $excludedNodes, true)) {
+                    continue;
+                }
+                $this->copyInlinableCssToStyleAttribute($this->ensureNodeIsElement($node), $cssRule);
+            }
+        }
+
+        if ($this->isInlineStyleAttributesParsingEnabled) {
+            $this->fillStyleAttributesWithMergedStyles();
+        }
+
+        $this->removeImportantAnnotationFromAllInlineStyles();
+
+        $this->determineMatchingUninlinableCssRules($cssRules['uninlinable']);
+        $this->copyUninlinableCssToStyleNode($parsedCss);
+
+        return $this;
+    }
+
+    /**
+     * Disables the parsing of inline styles.
+     *
+     * @return $this
+     */
+    public function disableInlineStyleAttributesParsing(): self
+    {
+        $this->isInlineStyleAttributesParsingEnabled = false;
+
+        return $this;
+    }
+
+    /**
+     * Disables the parsing of `<style>` blocks.
+     *
+     * @return $this
+     */
+    public function disableStyleBlocksParsing(): self
+    {
+        $this->isStyleBlocksParsingEnabled = false;
+
+        return $this;
+    }
+
+    /**
+     * Marks a media query type to keep.
+     *
+     * @param string $mediaName the media type name, e.g., "braille"
+     *
+     * @return $this
+     */
+    public function addAllowedMediaType(string $mediaName): self
+    {
+        $this->allowedMediaTypes[$mediaName] = true;
+
+        return $this;
+    }
+
+    /**
+     * Drops a media query type from the allowed list.
+     *
+     * @param string $mediaName the tag name, e.g., "braille"
+     *
+     * @return $this
+     */
+    public function removeAllowedMediaType(string $mediaName): self
+    {
+        if (isset($this->allowedMediaTypes[$mediaName])) {
+            unset($this->allowedMediaTypes[$mediaName]);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Adds a selector to exclude nodes from emogrification.
+     *
+     * Any nodes that match the selector will not have their style altered.
+     *
+     * @param string $selector the selector to exclude, e.g., ".editor"
+     *
+     * @return $this
+     */
+    public function addExcludedSelector(string $selector): self
+    {
+        $this->excludedSelectors[$selector] = true;
+
+        return $this;
+    }
+
+    /**
+     * No longer excludes the nodes matching this selector from emogrification.
+     *
+     * @param string $selector the selector to no longer exclude, e.g., ".editor"
+     *
+     * @return $this
+     */
+    public function removeExcludedSelector(string $selector): self
+    {
+        if (isset($this->excludedSelectors[$selector])) {
+            unset($this->excludedSelectors[$selector]);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Adds a selector to exclude CSS selector from emogrification.
+     *
+     * @param non-empty-string $selector the selector to exclude, e.g., `.editor`
+     *
+     * @return $this
+     */
+    public function addExcludedCssSelector(string $selector): self
+    {
+        $this->excludedCssSelectors[$selector] = true;
+
+        return $this;
+    }
+
+    /**
+     * No longer excludes the CSS selector from emogrification.
+     *
+     * @param non-empty-string $selector the selector to no longer exclude, e.g., `.editor`
+     *
+     * @return $this
+     */
+    public function removeExcludedCssSelector(string $selector): self
+    {
+        if (isset($this->excludedCssSelectors[$selector])) {
+            unset($this->excludedCssSelectors[$selector]);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Sets the debug mode.
+     *
+     * @param bool $debug set to true to enable debug mode
+     *
+     * @return $this
+     */
+    public function setDebug(bool $debug): self
+    {
+        $this->debug = $debug;
+
+        return $this;
+    }
+
+    /**
+     * Gets the array of selectors present in the CSS provided to `inlineCss()` for which the declarations could not be
+     * applied as inline styles, but which may affect elements in the HTML.  The relevant CSS will have been placed in a
+     * `<style>` element.  The selectors may include those used within `@media` rules or those involving dynamic
+     * pseudo-classes (such as `:hover`) or pseudo-elements (such as `::after`).
+     *
+     * @return array<array-key, string>
+     *
+     * @throws \BadMethodCallException if `inlineCss` has not been called first
+     */
+    public function getMatchingUninlinableSelectors(): array
+    {
+        return \array_column($this->getMatchingUninlinableCssRules(), 'selector');
+    }
+
+    /**
+     * @return array<array-key, array{
+     *             media: string,
+     *             selector: string,
+     *             hasUnmatchablePseudo: bool,
+     *             declarationsBlock: string,
+     *             line: int
+     *         }>
+     *
+     * @throws \BadMethodCallException if `inlineCss` has not been called first
+     */
+    private function getMatchingUninlinableCssRules(): array
+    {
+        if (!\is_array($this->matchingUninlinableCssRules)) {
+            throw new \BadMethodCallException('inlineCss must be called first', 1568385221);
+        }
+
+        return $this->matchingUninlinableCssRules;
+    }
+
+    /**
+     * Clears all caches.
+     */
+    private function clearAllCaches(): void
+    {
+        $this->caches = [
+            self::CACHE_KEY_SELECTOR => [],
+            self::CACHE_KEY_COMBINED_STYLES => [],
+        ];
+    }
+
+    /**
+     * Purges the visited nodes.
+     */
+    private function purgeVisitedNodes(): void
+    {
+        $this->visitedNodes = [];
+        $this->styleAttributesForNodes = [];
+    }
+
+    /**
+     * Parses the document and normalizes all existing CSS attributes.
+     * This changes 'DISPLAY: none' to 'display: none'.
+     * We wouldn't have to do this if DOMXPath supported XPath 2.0.
+     * Also stores a reference of nodes with existing inline styles so we don't overwrite them.
+     */
+    private function normalizeStyleAttributesOfAllNodes(): void
+    {
+        /** @var \DOMElement $node */
+        foreach ($this->getAllNodesWithStyleAttribute() as $node) {
+            if ($this->isInlineStyleAttributesParsingEnabled) {
+                $this->normalizeStyleAttributes($node);
+            }
+            // Remove style attribute in every case, so we can add them back (if inline style attributes
+            // parsing is enabled) to the end of the style list, thus keeping the right priority of CSS rules;
+            // else original inline style rules may remain at the beginning of the final inline style definition
+            // of a node, which may give not the desired results
+            $node->removeAttribute('style');
+        }
+    }
+
+    /**
+     * Returns a list with all DOM nodes that have a style attribute.
+     *
+     * @return \DOMNodeList
+     *
+     * @throws \RuntimeException
+     */
+    private function getAllNodesWithStyleAttribute(): \DOMNodeList
+    {
+        $query = '//*[@style]';
+        $matches = $this->getXPath()->query($query);
+        if (!$matches instanceof \DOMNodeList) {
+            throw new \RuntimeException('XPatch query failed: ' . $query, 1618577797);
+        }
+
+        return $matches;
+    }
+
+    /**
+     * Normalizes the value of the "style" attribute and saves it.
+     *
+     * @param \DOMElement $node
+     */
+    private function normalizeStyleAttributes(\DOMElement $node): void
+    {
+        $declarationBlockParser = new DeclarationBlockParser();
+
+        $normalizedOriginalStyle = (new Preg())->throwExceptions($this->debug)->replaceCallback(
+            '/-{0,2}+[_a-zA-Z][\\w\\-]*+(?=:)/S',
+            /** @param array<array-key, string> $propertyNameMatches */
+            static function (array $propertyNameMatches) use ($declarationBlockParser): string {
+                return $declarationBlockParser->normalizePropertyName($propertyNameMatches[0]);
+            },
+            $node->getAttribute('style')
+        );
+
+        // In order to not overwrite existing style attributes in the HTML, we have to save the original HTML styles.
+        $nodePath = $node->getNodePath();
+        if (\is_string($nodePath) && !isset($this->styleAttributesForNodes[$nodePath])) {
+            $this->styleAttributesForNodes[$nodePath] = $declarationBlockParser->parse($normalizedOriginalStyle);
+            $this->visitedNodes[$nodePath] = $node;
+        }
+
+        $node->setAttribute('style', $normalizedOriginalStyle);
+    }
+
+    /**
+     * Returns CSS content.
+     *
+     * @return string
+     */
+    private function getCssFromAllStyleNodes(): string
+    {
+        $styleNodes = $this->getXPath()->query('//style');
+        if ($styleNodes === false) {
+            return '';
+        }
+
+        $css = '';
+        foreach ($styleNodes as $styleNode) {
+            if (\is_string($styleNode->nodeValue)) {
+                $css .= "\n\n" . $styleNode->nodeValue;
+            }
+            $parentNode = $styleNode->parentNode;
+            if ($parentNode instanceof \DOMNode) {
+                $parentNode->removeChild($styleNode);
+            }
+        }
+
+        return $css;
+    }
+
+    /**
+     * Find the nodes that are not to be emogrified.
+     *
+     * @return list<\DOMElement>
+     *
+     * @throws ParseException in debug mode, if an invalid selector is encountered
+     * @throws \RuntimeException in debug mode, if `CssSelectorConverter::toXPath` returns an invalid XPath expression
+     * @throws \UnexpectedValueException if the selector query result includes a node which is not a `DOMElement`
+     */
+    private function getNodesToExclude(): array
+    {
+        $excludedNodes = [];
+        foreach (\array_keys($this->excludedSelectors) as $selectorToExclude) {
+            foreach ($this->querySelectorAll($selectorToExclude) as $node) {
+                $excludedNodes[] = $this->ensureNodeIsElement($node);
+            }
+        }
+
+        return $excludedNodes;
+    }
+
+    /**
+     * @param array{}|array{alwaysThrowParseException: bool} $options
+     *        This is an array of option values to control behaviour:
+     *        - `QSA_ALWAYS_THROW_PARSE_EXCEPTION` - `bool` - throw any `ParseException` regardless of debug setting.
+     *
+     * @return \DOMNodeList<\DOMNode> the HTML elements that match the provided CSS `$selectors`
+     *
+     * @throws ParseException
+     *         in debug mode (or with `QSA_ALWAYS_THROW_PARSE_EXCEPTION` option), if an invalid selector is encountered
+     * @throws \RuntimeException in debug mode, if `CssSelectorConverter::toXPath` returns an invalid XPath expression
+     */
+    private function querySelectorAll(string $selectors, array $options = []): \DOMNodeList
+    {
+        try {
+            $result = $this->getXPath()->query($this->getCssSelectorConverter()->toXPath($selectors));
+
+            if ($result === false) {
+                throw new \RuntimeException('query failed with selector \'' . $selectors . '\'', 1726533051);
+            }
+
+            return $result;
+        } catch (ParseException $exception) {
+            $alwaysThrowParseException = $options[self::QSA_ALWAYS_THROW_PARSE_EXCEPTION] ?? false;
+            if ($this->debug || $alwaysThrowParseException) {
+                throw $exception;
+            }
+            return new \DOMNodeList();
+        } catch (\RuntimeException $exception) {
+            if (
+                $this->debug
+            ) {
+                throw $exception;
+            }
+            // `RuntimeException` indicates a bug in CssSelector so pass the message to the error handler.
+            \trigger_error($exception->getMessage());
+            return new \DOMNodeList();
+        }
+    }
+
+    /**
+     * @throws \UnexpectedValueException if `$node` is not a `DOMElement`
+     */
+    private function ensureNodeIsElement(\DOMNode $node): \DOMElement
+    {
+        if (!$node instanceof \DOMElement) {
+            $path = $node->getNodePath() ?? '$node';
+            throw new \UnexpectedValueException($path . ' is not a DOMElement.', 1617975914);
+        }
+
+        return $node;
+    }
+
+    /**
+     * @return CssSelectorConverter
+     */
+    private function getCssSelectorConverter(): CssSelectorConverter
+    {
+        if (!$this->cssSelectorConverter instanceof CssSelectorConverter) {
+            $this->cssSelectorConverter = new CssSelectorConverter();
+        }
+
+        return $this->cssSelectorConverter;
+    }
+
+    /**
+     * Collates the individual rules from a `CssDocument` object.
+     *
+     * @param CssDocument $parsedCss
+     *
+     * @return array<string, array<array-key, array{
+     *           media: string,
+     *           selector: string,
+     *           hasUnmatchablePseudo: bool,
+     *           declarationsBlock: string,
+     *           line: int
+     *         }>>
+     *         This 2-entry array has the key "inlinable" containing rules which can be inlined as `style` attributes
+     *         and the key "uninlinable" containing rules which cannot.  Each value is an array of sub-arrays with the
+     *         following keys:
+     *         - "media" (the media query string, e.g. "@media screen and (max-width: 480px)",
+     *           or an empty string if not from a `@media` rule);
+     *         - "selector" (the CSS selector, e.g., "*" or "header h1");
+     *         - "hasUnmatchablePseudo" (`true` if that selector contains pseudo-elements or dynamic pseudo-classes such
+     *           that the declarations cannot be applied inline);
+     *         - "declarationsBlock" (the semicolon-separated CSS declarations for that selector,
+     *           e.g., `color: red; height: 4px;`);
+     *         - "line" (the line number, e.g. 42).
+     */
+    private function collateCssRules(CssDocument $parsedCss): array
+    {
+        $matches = $parsedCss->getStyleRulesData(\array_keys($this->allowedMediaTypes));
+
+        $preg = (new Preg())->throwExceptions($this->debug);
+        $cssRules = [
+            'inlinable' => [],
+            'uninlinable' => [],
+        ];
+        foreach ($matches as $key => $cssRule) {
+            if (!$cssRule->hasAtLeastOneDeclaration()) {
+                continue;
+            }
+
+            $mediaQuery = $cssRule->getContainingAtRule();
+            $declarationsBlock = $cssRule->getDeclarationAsText();
+            $selectors = $cssRule->getSelectors();
+
+            // Maybe exclude CSS selectors
+            if (\count($this->excludedCssSelectors) > 0) {
+                // Normalize spaces, line breaks & tabs
+                $selectorsNormalized = \array_map(static function (string $selector) use ($preg): string {
+                    return $preg->replace('@\\s++@u', ' ', $selector);
+                }, $selectors);
+
+                $selectors = \array_filter($selectorsNormalized, function (string $selector): bool {
+                    return !isset($this->excludedCssSelectors[$selector]);
+                });
+            }
+
+            foreach ($selectors as $selector) {
+                // don't process pseudo-elements and behavioral (dynamic) pseudo-classes;
+                // only allow structural pseudo-classes
+                $hasPseudoElement = \strpos($selector, '::') !== false;
+                $hasUnmatchablePseudo = $hasPseudoElement || $this->hasUnsupportedPseudoClass($selector);
+
+                $parsedCssRule = [
+                    'media' => $mediaQuery,
+                    'selector' => $selector,
+                    'hasUnmatchablePseudo' => $hasUnmatchablePseudo,
+                    'declarationsBlock' => $declarationsBlock,
+                    // keep track of where it appears in the file, since order is important
+                    'line' => $key,
+                ];
+                $ruleType = (!$cssRule->hasContainingAtRule() && !$hasUnmatchablePseudo) ? 'inlinable' : 'uninlinable';
+                $cssRules[$ruleType][] = $parsedCssRule;
+            }
+        }
+
+        \usort(
+            $cssRules['inlinable'],
+            /**
+             * @param array{selector: string, line: int, ...} $first
+             * @param array{selector: string, line: int, ...} $second
+             */
+            function (array $first, array $second): int {
+                return $this->sortBySelectorPrecedence($first, $second);
+            }
+        );
+
+        return $cssRules;
+    }
+
+    /**
+     * Tests if a selector contains a pseudo-class which would mean it cannot be converted to an XPath expression for
+     * inlining CSS declarations.
+     *
+     * Any pseudo class that does not match {@see PSEUDO_CLASS_MATCHER} cannot be converted.  Additionally, `...of-type`
+     * pseudo-classes cannot be converted if they are not associated with a type selector.
+     *
+     * @param string $selector
+     *
+     * @return bool
+     */
+    private function hasUnsupportedPseudoClass(string $selector): bool
+    {
+        $preg = (new Preg())->throwExceptions($this->debug);
+
+        if ($preg->match('/:(?!' . self::PSEUDO_CLASS_MATCHER . ')[\\w\\-]/i', $selector) !== 0) {
+            return true;
+        }
+
+        if ($preg->match('/:(?:' . self::OF_TYPE_PSEUDO_CLASS_MATCHER . ')/i', $selector) === 0) {
+            return false;
+        }
+
+        foreach ($preg->split('/' . self::COMBINATOR_MATCHER . '/', $selector) as $selectorPart) {
+            if ($this->selectorPartHasUnsupportedOfTypePseudoClass($selectorPart)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Tests if part of a selector contains an `...of-type` pseudo-class such that it cannot be converted to an XPath
+     * expression.
+     *
+     * @param string $selectorPart part of a selector which has been split up at combinators
+     *
+     * @return bool `true` if the selector part does not have a type but does have an `...of-type` pseudo-class
+     */
+    private function selectorPartHasUnsupportedOfTypePseudoClass(string $selectorPart): bool
+    {
+        $preg = (new Preg())->throwExceptions($this->debug);
+
+        if ($preg->match('/^[\\w\\-]/', $selectorPart) !== 0) {
+            return false;
+        }
+
+        return $preg->match('/:(?:' . self::OF_TYPE_PSEUDO_CLASS_MATCHER . ')/i', $selectorPart) !== 0;
+    }
+
+    /**
+     * @param array{selector: string, line: int, ...} $first
+     * @param array{selector: string, line: int, ...} $second
+     *
+     * @return int
+     */
+    private function sortBySelectorPrecedence(array $first, array $second): int
+    {
+        $precedenceOfFirst = $this->getCssSelectorPrecedence($first['selector']);
+        $precedenceOfSecond = $this->getCssSelectorPrecedence($second['selector']);
+
+        // We want these sorted in ascending order so selectors with lesser precedence get processed first and
+        // selectors with greater precedence get sorted last.
+        $precedenceForEquals = $first['line'] < $second['line'] ? -1 : 1;
+        $precedenceForNotEquals = $precedenceOfFirst < $precedenceOfSecond ? -1 : 1;
+        return ($precedenceOfFirst === $precedenceOfSecond) ? $precedenceForEquals : $precedenceForNotEquals;
+    }
+
+    /**
+     * @param string $selector
+     *
+     * @return int
+     */
+    private function getCssSelectorPrecedence(string $selector): int
+    {
+        $selectorKey = $selector;
+        if (isset($this->caches[self::CACHE_KEY_SELECTOR][$selectorKey])) {
+            return $this->caches[self::CACHE_KEY_SELECTOR][$selectorKey];
+        }
+
+        $preg = (new Preg())->throwExceptions($this->debug);
+        $precedence = 0;
+        foreach ($this->selectorPrecedenceMatchers as $matcher => $value) {
+            if (\trim($selector) === '') {
+                break;
+            }
+            $count = 0;
+            $selector = $preg->replace('/' . $matcher . '\\w+/', '', $selector, -1, $count);
+            $precedence += ($value * $count);
+        }
+        $this->caches[self::CACHE_KEY_SELECTOR][$selectorKey] = $precedence;
+
+        return $precedence;
+    }
+
+    /**
+     * Copies $cssRule into the style attribute of $node.
+     *
+     * Note: This method does not check whether $cssRule matches $node.
+     *
+     * @param \DOMElement $node
+     * @param array{
+     *            media: string,
+     *            selector: string,
+     *            hasUnmatchablePseudo: bool,
+     *            declarationsBlock: string,
+     *            line: int
+     *        } $cssRule
+     */
+    private function copyInlinableCssToStyleAttribute(\DOMElement $node, array $cssRule): void
+    {
+        $declarationsBlock = $cssRule['declarationsBlock'];
+        $declarationBlockParser = new DeclarationBlockParser();
+        $newStyleDeclarations = $declarationBlockParser->parse($declarationsBlock);
+        if ($newStyleDeclarations === []) {
+            return;
+        }
+
+        // if it has a style attribute, get it, process it, and append (overwrite) new stuff
+        if ($node->hasAttribute('style')) {
+            // break it up into an associative array
+            $oldStyleDeclarations = $declarationBlockParser->parse($node->getAttribute('style'));
+        } else {
+            $oldStyleDeclarations = [];
+        }
+        $node->setAttribute(
+            'style',
+            $this->generateStyleStringFromDeclarationsArrays($oldStyleDeclarations, $newStyleDeclarations)
+        );
+    }
+
+    /**
+     * This method merges old or existing name/value array with new name/value array
+     * and then generates a string of the combined style suitable for placing inline.
+     * This becomes the single point for CSS string generation allowing for consistent
+     * CSS output no matter where the CSS originally came from.
+     *
+     * @param array<string, string> $oldStyles
+     * @param array<string, string> $newStyles
+     *
+     * @return string
+     *
+     * @throws \UnexpectedValueException if an empty property name is encountered (which should not happen)
+     */
+    private function generateStyleStringFromDeclarationsArrays(array $oldStyles, array $newStyles): string
+    {
+        $cacheKey = \serialize([$oldStyles, $newStyles]);
+        if (isset($this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey])) {
+            return $this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey];
+        }
+
+        // Unset the overridden styles to preserve order, important if shorthand and individual properties are mixed
+        foreach ($oldStyles as $attributeName => $attributeValue) {
+            if (!isset($newStyles[$attributeName])) {
+                continue;
+            }
+
+            $newAttributeValue = $newStyles[$attributeName];
+            if (
+                $this->attributeValueIsImportant($attributeValue)
+                && !$this->attributeValueIsImportant($newAttributeValue)
+            ) {
+                unset($newStyles[$attributeName]);
+            } else {
+                unset($oldStyles[$attributeName]);
+            }
+        }
+
+        $combinedStyles = \array_merge($oldStyles, $newStyles);
+
+        $declarationBlockParser = new DeclarationBlockParser();
+        $style = '';
+        foreach ($combinedStyles as $attributeName => $attributeValue) {
+            $trimmedAttributeName = \trim($attributeName);
+            if ($trimmedAttributeName === '') {
+                throw new \UnexpectedValueException('An empty property name was encountered.', 1727046078);
+            }
+            $propertyName = $declarationBlockParser->normalizePropertyName($trimmedAttributeName);
+            $propertyValue = \trim($attributeValue);
+            $style .= $propertyName . ': ' . $propertyValue . '; ';
+        }
+        $trimmedStyle = \rtrim($style);
+
+        $this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey] = $trimmedStyle;
+
+        return $trimmedStyle;
+    }
+
+    /**
+     * Checks whether $attributeValue is marked as !important.
+     *
+     * @param string $attributeValue
+     *
+     * @return bool
+     */
+    private function attributeValueIsImportant(string $attributeValue): bool
+    {
+        return (new Preg())->throwExceptions($this->debug)->match('/!\\s*+important$/i', $attributeValue) !== 0;
+    }
+
+    /**
+     * Merges styles from styles attributes and style nodes and applies them to the attribute nodes
+     */
+    private function fillStyleAttributesWithMergedStyles(): void
+    {
+        $declarationBlockParser = new DeclarationBlockParser();
+        foreach ($this->styleAttributesForNodes as $nodePath => $styleAttributesForNode) {
+            $node = $this->visitedNodes[$nodePath];
+            $currentStyleAttributes = $declarationBlockParser->parse($node->getAttribute('style'));
+            $node->setAttribute(
+                'style',
+                $this->generateStyleStringFromDeclarationsArrays(
+                    $currentStyleAttributes,
+                    $styleAttributesForNode
+                )
+            );
+        }
+    }
+
+    /**
+     * Searches for all nodes with a style attribute and removes the "!important" annotations out of
+     * the inline style declarations, eventually by rearranging declarations.
+     *
+     * @throws \RuntimeException
+     */
+    private function removeImportantAnnotationFromAllInlineStyles(): void
+    {
+        /** @var \DOMElement $node */
+        foreach ($this->getAllNodesWithStyleAttribute() as $node) {
+            $this->removeImportantAnnotationFromNodeInlineStyle($node);
+        }
+    }
+
+    /**
+     * Removes the "!important" annotations out of the inline style declarations,
+     * eventually by rearranging declarations.
+     * Rearranging needed when !important shorthand properties are followed by some of their
+     * not !important expanded-version properties.
+     * For example "font: 12px serif !important; font-size: 13px;" must be reordered
+     * to "font-size: 13px; font: 12px serif;" in order to remain correct.
+     *
+     * @param \DOMElement $node
+     *
+     * @throws \RuntimeException
+     */
+    private function removeImportantAnnotationFromNodeInlineStyle(\DOMElement $node): void
+    {
+        $style = $node->getAttribute('style');
+        $inlineStyleDeclarations = (new DeclarationBlockParser())->parse((bool) $style ? $style : '');
+        /** @var array<string, string> $regularStyleDeclarations */
+        $regularStyleDeclarations = [];
+        /** @var array<string, string> $importantStyleDeclarations */
+        $importantStyleDeclarations = [];
+        foreach ($inlineStyleDeclarations as $property => $value) {
+            if ($this->attributeValueIsImportant($value)) {
+                $importantStyleDeclarations[$property]
+                    = (new Preg())->throwExceptions($this->debug)->replace('/\\s*+!\\s*+important$/i', '', $value);
+            } else {
+                $regularStyleDeclarations[$property] = $value;
+            }
+        }
+        $inlineStyleDeclarationsInNewOrder = \array_merge($regularStyleDeclarations, $importantStyleDeclarations);
+        $node->setAttribute(
+            'style',
+            $this->generateStyleStringFromSingleDeclarationsArray($inlineStyleDeclarationsInNewOrder)
+        );
+    }
+
+    /**
+     * Generates a CSS style string suitable to be used inline from the $styleDeclarations property => value array.
+     *
+     * @param array<string, string> $styleDeclarations
+     *
+     * @return string
+     */
+    private function generateStyleStringFromSingleDeclarationsArray(array $styleDeclarations): string
+    {
+        return $this->generateStyleStringFromDeclarationsArrays([], $styleDeclarations);
+    }
+
+    /**
+     * Determines which of `$cssRules` actually apply to `$this->domDocument`, and sets them in
+     * `$this->matchingUninlinableCssRules`.
+     *
+     * @param array<array-key, array{
+     *            media: string,
+     *            selector: string,
+     *            hasUnmatchablePseudo: bool,
+     *            declarationsBlock: string,
+     *            line: int
+     *        }> $cssRules
+     *        the "uninlinable" array of CSS rules returned by `collateCssRules`
+     */
+    private function determineMatchingUninlinableCssRules(array $cssRules): void
+    {
+        $this->matchingUninlinableCssRules = \array_filter(
+            $cssRules,
+            function (array $cssRule): bool {
+                return $this->existsMatchForSelectorInCssRule($cssRule);
+            }
+        );
+    }
+
+    /**
+     * Checks whether there is at least one matching element for the CSS selector contained in the `selector` element
+     * of the provided CSS rule.
+     *
+     * Any dynamic pseudo-classes will be assumed to apply. If the selector matches a pseudo-element,
+     * it will test for a match with its originating element.
+     *
+     * @param array{
+     *            media: string,
+     *            selector: string,
+     *            hasUnmatchablePseudo: bool,
+     *            declarationsBlock: string,
+     *            line: int
+     *        } $cssRule
+     *
+     * @return bool
+     *
+     * @throws ParseException
+     */
+    private function existsMatchForSelectorInCssRule(array $cssRule): bool
+    {
+        $selector = $cssRule['selector'];
+        if ($cssRule['hasUnmatchablePseudo']) {
+            $selector = $this->removeUnmatchablePseudoComponents($selector);
+        }
+        return $this->existsMatchForCssSelector($selector);
+    }
+
+    /**
+     * Checks whether there is at least one matching element for $cssSelector.
+     * When not in debug mode, it returns true also for invalid selectors (because they may be valid,
+     * just not implemented/recognized yet by Emogrifier).
+     *
+     * @param string $cssSelector
+     *
+     * @return bool
+     *
+     * @throws ParseException in debug mode, if an invalid selector is encountered
+     * @throws \RuntimeException in debug mode, if `CssSelectorConverter::toXPath` returns an invalid XPath expression
+     */
+    private function existsMatchForCssSelector(string $cssSelector): bool
+    {
+        try {
+            $nodesMatchingSelector
+                = $this->querySelectorAll($cssSelector, [self::QSA_ALWAYS_THROW_PARSE_EXCEPTION => true]);
+        } catch (ParseException $e) {
+            if ($this->debug) {
+                throw $e;
+            }
+            return true;
+        }
+
+        return $nodesMatchingSelector->length !== 0;
+    }
+
+    /**
+     * Removes pseudo-elements and dynamic pseudo-classes from a CSS selector, replacing them with "*" if necessary.
+     * If such a pseudo-component is within the argument of `:not`, the entire `:not` component is removed or replaced.
+     *
+     * @param string $selector
+     *
+     * @return string
+     *         selector which will match the relevant DOM elements if the pseudo-classes are assumed to apply, or in the
+     *         case of pseudo-elements will match their originating element
+     */
+    private function removeUnmatchablePseudoComponents(string $selector): string
+    {
+        $preg = (new Preg())->throwExceptions($this->debug);
+
+        // The regex allows nested brackets via `(?2)`.
+        // A space is temporarily prepended because the callback can't determine if the match was at the very start.
+        $selectorWithoutNots = \ltrim((new Preg())->throwExceptions($this->debug)->replaceCallback(
+            '/([\\s>+~]?+):not(\\([^()]*+(?:(?2)[^()]*+)*+\\))/i',
+            /** @param array<array-key, string> $matches */
+            function (array $matches): string {
+                return $this->replaceUnmatchableNotComponent($matches);
+            },
+            ' ' . $selector
+        ));
+
+        $selectorWithoutUnmatchablePseudoComponents = $this->removeSelectorComponents(
+            ':(?!' . self::PSEUDO_CLASS_MATCHER . '):?+[\\w\\-]++(?:\\([^\\)]*+\\))?+',
+            $selectorWithoutNots
+        );
+
+        if (
+            $preg->match(
+                '/:(?:' . self::OF_TYPE_PSEUDO_CLASS_MATCHER . ')/i',
+                $selectorWithoutUnmatchablePseudoComponents
+            )
+            === 0
+        ) {
+            return $selectorWithoutUnmatchablePseudoComponents;
+        }
+        return \implode('', \array_map(
+            function (string $selectorPart): string {
+                return $this->removeUnsupportedOfTypePseudoClasses($selectorPart);
+            },
+            $preg->split(
+                '/(' . self::COMBINATOR_MATCHER . ')/',
+                $selectorWithoutUnmatchablePseudoComponents,
+                -1,
+                PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY
+            )
+        ));
+    }
+
+    /**
+     * Helps `removeUnmatchablePseudoComponents()` replace or remove a selector `:not(...)` component if its argument
+     * contains pseudo-elements or dynamic pseudo-classes.
+     *
+     * @param array<array-key, string> $matches array of elements matched by the regular expression
+     *
+     * @return string
+     *         the full match if there were no unmatchable pseudo components within; otherwise, any preceding combinator
+     *         followed by "*", or an empty string if there was no preceding combinator
+     */
+    private function replaceUnmatchableNotComponent(array $matches): string
+    {
+        [$notComponentWithAnyPrecedingCombinator, $anyPrecedingCombinator, $notArgumentInBrackets] = $matches;
+
+        if ($this->hasUnsupportedPseudoClass($notArgumentInBrackets)) {
+            return $anyPrecedingCombinator !== '' ? $anyPrecedingCombinator . '*' : '';
+        }
+        return $notComponentWithAnyPrecedingCombinator;
+    }
+
+    /**
+     * Removes components from a CSS selector, replacing them with "*" if necessary.
+     *
+     * @param string $matcher regular expression part to match the components to remove
+     * @param string $selector
+     *
+     * @return string
+     *         selector which will match the relevant DOM elements if the removed components are assumed to apply (or in
+     *         the case of pseudo-elements will match their originating element)
+     */
+    private function removeSelectorComponents(string $matcher, string $selector): string
+    {
+        return (new Preg())->throwExceptions($this->debug)->replace(
+            ['/([\\s>+~]|^)' . $matcher . '/i', '/' . $matcher . '/i'],
+            ['$1*', ''],
+            $selector
+        );
+    }
+
+    /**
+     * Removes any `...-of-type` pseudo-classes from part of a CSS selector, if it does not have a type, replacing them
+     * with "*" if necessary.
+     *
+     * @param string $selectorPart part of a selector which has been split up at combinators
+     *
+     * @return string
+     *         selector part which will match the relevant DOM elements if the pseudo-classes are assumed to apply
+     */
+    private function removeUnsupportedOfTypePseudoClasses(string $selectorPart): string
+    {
+        if (!$this->selectorPartHasUnsupportedOfTypePseudoClass($selectorPart)) {
+            return $selectorPart;
+        }
+
+        return $this->removeSelectorComponents(
+            ':(?:' . self::OF_TYPE_PSEUDO_CLASS_MATCHER . ')(?:\\([^\\)]*+\\))?+',
+            $selectorPart
+        );
+    }
+
+    /**
+     * Applies `$this->matchingUninlinableCssRules` to `$this->domDocument` by placing them as CSS in a `<style>`
+     * element.
+     * If there are no uninlinable CSS rules to copy there, a `<style>` element will be created containing only the
+     * applicable at-rules from `$parsedCss`.
+     * If there are none of either, an empty `<style>` element will not be created.
+     *
+     * @param CssDocument $parsedCss
+     *        This may contain various at-rules whose content `CssInliner` does not currently attempt to inline or
+     *        process in any other way, such as `@import`, `@font-face`, `@keyframes`, etc., and which should precede
+     *        the processed but found-to-be-uninlinable CSS placed in the `<style>` element.
+     *        Note that `CssInliner` processes `@media` rules so that they can be ordered correctly with respect to
+     *        other uninlinable rules; these will not be duplicated from `$parsedCss`.
+     */
+    private function copyUninlinableCssToStyleNode(CssDocument $parsedCss): void
+    {
+        $css = $parsedCss->renderNonConditionalAtRules();
+
+        // avoid including unneeded class dependency if there are no rules
+        if ($this->getMatchingUninlinableCssRules() !== []) {
+            $cssConcatenator = new CssConcatenator();
+            foreach ($this->getMatchingUninlinableCssRules() as $cssRule) {
+                $cssConcatenator->append([$cssRule['selector']], $cssRule['declarationsBlock'], $cssRule['media']);
+            }
+            $css .= $cssConcatenator->getCss();
+        }
+
+        // avoid adding empty style element
+        if ($css !== '') {
+            $this->addStyleElementToDocument($css);
+        }
+    }
+
+    /**
+     * Adds a style element with $css to $this->domDocument.
+     *
+     * This method is protected to allow overriding.
+     *
+     * @see https://github.com/MyIntervals/emogrifier/issues/103
+     *
+     * @param string $css
+     */
+    protected function addStyleElementToDocument(string $css): void
+    {
+        $domDocument = $this->getDomDocument();
+        $styleElement = $domDocument->createElement('style', $css);
+        $styleAttribute = $domDocument->createAttribute('type');
+        $styleAttribute->value = 'text/css';
+        $styleElement->appendChild($styleAttribute);
+
+        $headElement = $this->getHeadElement();
+        $headElement->appendChild($styleElement);
+    }
+
+    /**
+     * Returns the HEAD element.
+     *
+     * This method assumes that there always is a HEAD element.
+     *
+     * @return \DOMElement
+     *
+     * @throws \UnexpectedValueException
+     */
+    private function getHeadElement(): \DOMElement
+    {
+        $node = $this->getDomDocument()->getElementsByTagName('head')->item(0);
+        if (!$node instanceof \DOMElement) {
+            throw new \UnexpectedValueException('There is no HEAD element. This should never happen.', 1617923227);
+        }
+
+        return $node;
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/AbstractHtmlProcessor.php b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/AbstractHtmlProcessor.php
new file mode 100644
index 0000000..683310a
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/AbstractHtmlProcessor.php
@@ -0,0 +1,478 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\HtmlProcessor;
+
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\Preg;
+
+/**
+ * Base class for HTML processor that e.g., can remove, add or modify nodes or attributes.
+ *
+ * The "vanilla" subclass is the HtmlNormalizer.
+ */
+abstract class AbstractHtmlProcessor
+{
+    /**
+     * @var string
+     */
+    protected const DEFAULT_DOCUMENT_TYPE = '<!DOCTYPE html>';
+
+    /**
+     * @var string
+     */
+    protected const CONTENT_TYPE_META_TAG = '<meta http-equiv="Content-Type" content="text/html; charset=utf-8">';
+
+    /**
+     * @var string Regular expression part to match tag names that PHP's DOMDocument implementation is not aware are
+     *      self-closing. These are mostly HTML5 elements, but for completeness <command> (obsolete) and <keygen>
+     *      (deprecated) are also included.
+     *
+     * @see https://bugs.php.net/bug.php?id=73175
+     */
+    protected const PHP_UNRECOGNIZED_VOID_TAGNAME_MATCHER = '(?:command|embed|keygen|source|track|wbr)';
+
+    /**
+     * Regular expression part to match tag names that may appear before the start of the `<body>` element.  A start tag
+     * for any other element would implicitly start the `<body>` element due to tag omission rules.
+     *
+     * @var string
+     */
+    protected const TAGNAME_ALLOWED_BEFORE_BODY_MATCHER
+        = '(?:html|head|base|command|link|meta|noscript|script|style|template|title)';
+
+    /**
+     * regular expression pattern to match an HTML comment, including delimiters and modifiers
+     *
+     * @var string
+     */
+    protected const HTML_COMMENT_PATTERN = '/<!--[^-]*+(?:-(?!->)[^-]*+)*+(?:-->|$)/';
+
+    /**
+     * regular expression pattern to match an HTML `<template>` element, including delimiters and modifiers
+     *
+     * @var string
+     */
+    protected const HTML_TEMPLATE_ELEMENT_PATTERN
+        = '%<template[\\s>][^<]*+(?:<(?!/template>)[^<]*+)*+(?:</template>|$)%i';
+
+    /**
+     * @var ?\DOMDocument
+     */
+    protected $domDocument = null;
+
+    /**
+     * @var ?\DOMXPath
+     */
+    private $xPath = null;
+
+    /**
+     * The constructor.
+     *
+     * Please use `::fromHtml` or `::fromDomDocument` instead.
+     */
+    private function __construct() {}
+
+    /**
+     * Builds a new instance from the given HTML.
+     *
+     * @param string $unprocessedHtml raw HTML, must be UTF-encoded, must not be empty
+     *
+     * @return static
+     *
+     * @throws \InvalidArgumentException if $unprocessedHtml is anything other than a non-empty string
+     */
+    public static function fromHtml(string $unprocessedHtml): self
+    {
+        if ($unprocessedHtml === '') {
+            throw new \InvalidArgumentException('The provided HTML must not be empty.', 1515763647);
+        }
+
+        $instance = new static();
+        $instance->setHtml($unprocessedHtml);
+
+        return $instance;
+    }
+
+    /**
+     * Builds a new instance from the given DOM document.
+     *
+     * @param \DOMDocument $document a DOM document returned by getDomDocument() of another instance
+     *
+     * @return static
+     */
+    public static function fromDomDocument(\DOMDocument $document): self
+    {
+        $instance = new static();
+        $instance->setDomDocument($document);
+
+        return $instance;
+    }
+
+    /**
+     * Sets the HTML to process.
+     *
+     * @param string $html the HTML to process, must be UTF-8-encoded
+     */
+    private function setHtml(string $html): void
+    {
+        $this->createUnifiedDomDocument($html);
+    }
+
+    /**
+     * Provides access to the internal DOMDocument representation of the HTML in its current state.
+     *
+     * @return \DOMDocument
+     *
+     * @throws \UnexpectedValueException
+     */
+    public function getDomDocument(): \DOMDocument
+    {
+        if (!$this->domDocument instanceof \DOMDocument) {
+            $message = self::class . '::setDomDocument() has not yet been called on ' . static::class;
+            throw new \UnexpectedValueException($message, 1570472239);
+        }
+
+        return $this->domDocument;
+    }
+
+    /**
+     * @param \DOMDocument $domDocument
+     */
+    private function setDomDocument(\DOMDocument $domDocument): void
+    {
+        $this->domDocument = $domDocument;
+        $this->xPath = new \DOMXPath($this->domDocument);
+    }
+
+    /**
+     * @return \DOMXPath
+     *
+     * @throws \UnexpectedValueException
+     */
+    protected function getXPath(): \DOMXPath
+    {
+        if (!$this->xPath instanceof \DOMXPath) {
+            $message = self::class . '::setDomDocument() has not yet been called on ' . static::class;
+            throw new \UnexpectedValueException($message, 1617819086);
+        }
+
+        return $this->xPath;
+    }
+
+    /**
+     * Renders the normalized and processed HTML.
+     *
+     * @return string
+     */
+    public function render(): string
+    {
+        $htmlWithPossibleErroneousClosingTags = $this->getDomDocument()->saveHTML();
+
+        return $this->removeSelfClosingTagsClosingTags($htmlWithPossibleErroneousClosingTags);
+    }
+
+    /**
+     * Renders the content of the BODY element of the normalized and processed HTML.
+     *
+     * @return string
+     */
+    public function renderBodyContent(): string
+    {
+        $htmlWithPossibleErroneousClosingTags = $this->getDomDocument()->saveHTML($this->getBodyElement());
+        $bodyNodeHtml = $this->removeSelfClosingTagsClosingTags($htmlWithPossibleErroneousClosingTags);
+
+        return (new Preg())->replace('%</?+body(?:\\s[^>]*+)?+>%', '', $bodyNodeHtml);
+    }
+
+    /**
+     * Eliminates any invalid closing tags for void elements from the given HTML.
+     *
+     * @param string $html
+     *
+     * @return string
+     */
+    private function removeSelfClosingTagsClosingTags(string $html): string
+    {
+        return (new Preg())->replace('%</' . self::PHP_UNRECOGNIZED_VOID_TAGNAME_MATCHER . '>%', '', $html);
+    }
+
+    /**
+     * Returns the HTML element.
+     *
+     * This method assumes that there always is an HTML element, throwing an exception otherwise.
+     *
+     * @throws \UnexpectedValueException
+     */
+    protected function getHtmlElement(): \DOMElement
+    {
+        $htmlElement = $this->getDomDocument()->getElementsByTagName('html')->item(0);
+        if (!$htmlElement instanceof \DOMElement) {
+            throw new \UnexpectedValueException('There is no HTML element although there should be one.', 1569930853);
+        }
+
+        return $htmlElement;
+    }
+
+    /**
+     * Returns the BODY element.
+     *
+     * This method assumes that there always is a BODY element.
+     *
+     * @return \DOMElement
+     *
+     * @throws \RuntimeException
+     */
+    private function getBodyElement(): \DOMElement
+    {
+        $node = $this->getDomDocument()->getElementsByTagName('body')->item(0);
+        if (!$node instanceof \DOMElement) {
+            throw new \RuntimeException('There is no body element.', 1617922607);
+        }
+
+        return $node;
+    }
+
+    /**
+     * Creates a DOM document from the given HTML and stores it in $this->domDocument.
+     *
+     * The DOM document will always have a BODY element and a document type.
+     *
+     * @param string $html
+     */
+    private function createUnifiedDomDocument(string $html): void
+    {
+        $this->createRawDomDocument($html);
+        $this->ensureExistenceOfBodyElement();
+    }
+
+    /**
+     * Creates a DOMDocument instance from the given HTML and stores it in $this->domDocument.
+     *
+     * @param string $html
+     */
+    private function createRawDomDocument(string $html): void
+    {
+        $domDocument = new \DOMDocument();
+        $domDocument->strictErrorChecking = false;
+        $domDocument->formatOutput = false;
+        $libXmlState = \libxml_use_internal_errors(true);
+        $domDocument->loadHTML($this->prepareHtmlForDomConversion($html));
+        \libxml_clear_errors();
+        \libxml_use_internal_errors($libXmlState);
+
+        $this->setDomDocument($domDocument);
+    }
+
+    /**
+     * Returns the HTML with added document type, Content-Type meta tag, and self-closing slashes, if needed,
+     * ensuring that the HTML will be good for creating a DOM document from it.
+     *
+     * @param string $html
+     *
+     * @return string the unified HTML
+     */
+    private function prepareHtmlForDomConversion(string $html): string
+    {
+        $htmlWithSelfClosingSlashes = $this->ensurePhpUnrecognizedSelfClosingTagsAreXml($html);
+        $htmlWithDocumentType = $this->ensureDocumentType($htmlWithSelfClosingSlashes);
+
+        return $this->addContentTypeMetaTag($htmlWithDocumentType);
+    }
+
+    /**
+     * Makes sure that the passed HTML has a document type, with lowercase "html".
+     *
+     * @param string $html
+     *
+     * @return string HTML with document type
+     */
+    private function ensureDocumentType(string $html): string
+    {
+        $hasDocumentType = \stripos($html, '<!DOCTYPE') !== false;
+        if ($hasDocumentType) {
+            return $this->normalizeDocumentType($html);
+        }
+
+        return self::DEFAULT_DOCUMENT_TYPE . $html;
+    }
+
+    /**
+     * Makes sure the document type in the passed HTML has lowercase "html".
+     *
+     * @param string $html
+     *
+     * @return string HTML with normalized document type
+     */
+    private function normalizeDocumentType(string $html): string
+    {
+        // Limit to replacing the first occurrence: as an optimization; and in case an example exists as unescaped text.
+        return (new Preg())->replace(
+            '/<!DOCTYPE\\s++html(?=[\\s>])/i',
+            '<!DOCTYPE html',
+            $html,
+            1
+        );
+    }
+
+    /**
+     * Adds a Content-Type meta tag for the charset.
+     *
+     * This method also ensures that there is a HEAD element.
+     *
+     * @param string $html
+     *
+     * @return string the HTML with the meta tag added
+     */
+    private function addContentTypeMetaTag(string $html): string
+    {
+        if ($this->hasContentTypeMetaTagInHead($html)) {
+            return $html;
+        }
+
+        // We are trying to insert the meta tag to the right spot in the DOM.
+        // If we just prepended it to the HTML, we would lose attributes set to the HTML tag.
+        $hasHeadTag = (new Preg())->match('/<head[\\s>]/i', $html) !== 0;
+        $hasHtmlTag = \stripos($html, '<html') !== false;
+
+        if ($hasHeadTag) {
+            $reworkedHtml = (new Preg())->replace(
+                '/<head(?=[\\s>])([^>]*+)>/i',
+                '<head$1>' . self::CONTENT_TYPE_META_TAG,
+                $html
+            );
+        } elseif ($hasHtmlTag) {
+            $reworkedHtml = (new Preg())->replace(
+                '/<html(.*?)>/is',
+                '<html$1><head>' . self::CONTENT_TYPE_META_TAG . '</head>',
+                $html
+            );
+        } else {
+            $reworkedHtml = self::CONTENT_TYPE_META_TAG . $html;
+        }
+
+        return $reworkedHtml;
+    }
+
+    /**
+     * Tests whether the given HTML has a valid `Content-Type` metadata element within the `<head>` element.  Due to tag
+     * omission rules, HTML parsers are expected to end the `<head>` element and start the `<body>` element upon
+     * encountering a start tag for any element which is permitted only within the `<body>`.
+     *
+     * @param string $html
+     *
+     * @return bool
+     */
+    private function hasContentTypeMetaTagInHead(string $html): bool
+    {
+        (new Preg())->match(
+            '%^.*?(?=<meta(?=\\s)[^>]*\\shttp-equiv=(["\']?+)Content-Type\\g{-1}[\\s/>])%is',
+            $html,
+            $matches
+        );
+        if (isset($matches[0])) {
+            $htmlBefore = $matches[0];
+            try {
+                $hasContentTypeMetaTagInHead = !$this->hasEndOfHeadElement($htmlBefore);
+            } catch (\RuntimeException $exception) {
+                // If something unexpected occurs, assume the `Content-Type` that was found is valid.
+                \trigger_error($exception->getMessage());
+                $hasContentTypeMetaTagInHead = true;
+            }
+        } else {
+            $hasContentTypeMetaTagInHead = false;
+        }
+
+        return $hasContentTypeMetaTagInHead;
+    }
+
+    /**
+     * Tests whether the `<head>` element ends within the given HTML.  Due to tag omission rules, HTML parsers are
+     * expected to end the `<head>` element and start the `<body>` element upon encountering a start tag for any element
+     * which is permitted only within the `<body>`.
+     *
+     * @param string $html
+     *
+     * @return bool
+     *
+     * @throws \RuntimeException
+     */
+    private function hasEndOfHeadElement(string $html): bool
+    {
+        if (
+            (new Preg())->match('%<(?!' . self::TAGNAME_ALLOWED_BEFORE_BODY_MATCHER . '[\\s/>])\\w|</head>%i', $html)
+            !== 0
+        ) {
+            // An exception to the implicit end of the `<head>` is any content within a `<template>` element, as well in
+            // comments.  As an optimization, this is only checked for if a potential `<head>` end tag is found.
+            $htmlWithoutCommentsOrTemplates = $this->removeHtmlTemplateElements($this->removeHtmlComments($html));
+            $hasEndOfHeadElement = $htmlWithoutCommentsOrTemplates === $html
+                || $this->hasEndOfHeadElement($htmlWithoutCommentsOrTemplates);
+        } else {
+            $hasEndOfHeadElement = false;
+        }
+
+        return $hasEndOfHeadElement;
+    }
+
+    /**
+     * Removes comments from the given HTML, including any which are unterminated, for which the remainder of the string
+     * is removed.
+     *
+     * @param string $html
+     *
+     * @return string
+     *
+     * @throws \RuntimeException
+     */
+    private function removeHtmlComments(string $html): string
+    {
+        return (new Preg())->throwExceptions(true)->replace(self::HTML_COMMENT_PATTERN, '', $html);
+    }
+
+    /**
+     * Removes `<template>` elements from the given HTML, including any without an end tag, for which the remainder of
+     * the string is removed.
+     *
+     * @param string $html
+     *
+     * @return string
+     *
+     * @throws \RuntimeException
+     */
+    private function removeHtmlTemplateElements(string $html): string
+    {
+        return (new Preg())->throwExceptions(true)->replace(self::HTML_TEMPLATE_ELEMENT_PATTERN, '', $html);
+    }
+
+    /**
+     * Makes sure that any self-closing tags not recognized as such by PHP's DOMDocument implementation have a
+     * self-closing slash.
+     *
+     * @param string $html
+     *
+     * @return string HTML with problematic tags converted.
+     */
+    private function ensurePhpUnrecognizedSelfClosingTagsAreXml(string $html): string
+    {
+        return (new Preg())->replace(
+            '%<' . self::PHP_UNRECOGNIZED_VOID_TAGNAME_MATCHER . '\\b[^>]*+(?<!/)(?=>)%',
+            '$0/',
+            $html
+        );
+    }
+
+    /**
+     * Checks that $this->domDocument has a BODY element and adds it if it is missing.
+     *
+     * @throws \UnexpectedValueException
+     */
+    private function ensureExistenceOfBodyElement(): void
+    {
+        if ($this->getDomDocument()->getElementsByTagName('body')->item(0) instanceof \DOMElement) {
+            return;
+        }
+
+        $this->getHtmlElement()->appendChild($this->getDomDocument()->createElement('body'));
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssToAttributeConverter.php b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssToAttributeConverter.php
new file mode 100644
index 0000000..c9b9c74
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssToAttributeConverter.php
@@ -0,0 +1,261 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\HtmlProcessor;
+
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\DeclarationBlockParser;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\Preg;
+
+/**
+ * This HtmlProcessor can convert style HTML attributes to the corresponding other visual HTML attributes,
+ * e.g. it converts style="width: 100px" to width="100".
+ *
+ * It will only add attributes, but leaves the style attribute untouched.
+ *
+ * To trigger the conversion, call the convertCssToVisualAttributes method.
+ */
+final class CssToAttributeConverter extends AbstractHtmlProcessor
+{
+    /**
+     * This multi-level array contains simple mappings of CSS properties to
+     * HTML attributes. If a mapping only applies to certain HTML nodes or
+     * only for certain values, the mapping is an object with an allowlist
+     * of nodes and values.
+     *
+     * @var array<string, array{attribute: string, nodes?: array<int, string>, values?: array<int, string>}>
+     */
+    private $cssToHtmlMap = [
+        'background-color' => [
+            'attribute' => 'bgcolor',
+        ],
+        'text-align' => [
+            'attribute' => 'align',
+            'nodes' => ['p', 'div', 'td', 'th'],
+            'values' => ['left', 'right', 'center', 'justify'],
+        ],
+        'float' => [
+            'attribute' => 'align',
+            'nodes' => ['table', 'img'],
+            'values' => ['left', 'right'],
+        ],
+        'border-spacing' => [
+            'attribute' => 'cellspacing',
+            'nodes' => ['table'],
+        ],
+    ];
+
+    /**
+     * Maps the CSS from the style nodes to visual HTML attributes.
+     *
+     * @return $this
+     */
+    public function convertCssToVisualAttributes(): self
+    {
+        $declarationBlockParser = new DeclarationBlockParser();
+        /** @var \DOMElement $node */
+        foreach ($this->getAllNodesWithStyleAttribute() as $node) {
+            $inlineStyleDeclarations = $declarationBlockParser->parse($node->getAttribute('style'));
+            $this->mapCssToHtmlAttributes($inlineStyleDeclarations, $node);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Returns a list with all DOM nodes that have a style attribute.
+     *
+     * @return \DOMNodeList
+     */
+    private function getAllNodesWithStyleAttribute(): \DOMNodeList
+    {
+        return $this->getXPath()->query('//*[@style]');
+    }
+
+    /**
+     * Applies $styles to $node.
+     *
+     * This method maps CSS styles to HTML attributes and adds those to the
+     * node.
+     *
+     * @param array<string, string> $styles the new CSS styles taken from the global styles to be applied to this node
+     * @param \DOMElement $node node to apply styles to
+     */
+    private function mapCssToHtmlAttributes(array $styles, \DOMElement $node): void
+    {
+        foreach ($styles as $property => $value) {
+            // Strip !important indicator
+            $value = \trim(\str_replace('!important', '', $value));
+            $this->mapCssToHtmlAttribute($property, $value, $node);
+        }
+    }
+
+    /**
+     * Tries to apply the CSS style to $node as an attribute.
+     *
+     * This method maps a CSS rule to HTML attributes and adds those to the node.
+     *
+     * @param string $property the name of the CSS property to map
+     * @param string $value the value of the style rule to map
+     * @param \DOMElement $node node to apply styles to
+     */
+    private function mapCssToHtmlAttribute(string $property, string $value, \DOMElement $node): void
+    {
+        if (!$this->mapSimpleCssProperty($property, $value, $node)) {
+            $this->mapComplexCssProperty($property, $value, $node);
+        }
+    }
+
+    /**
+     * Looks up the CSS property in the mapping table and maps it if it matches the conditions.
+     *
+     * @param string $property the name of the CSS property to map
+     * @param string $value the value of the style rule to map
+     * @param \DOMElement $node node to apply styles to
+     *
+     * @return bool true if the property can be mapped using the simple mapping table
+     */
+    private function mapSimpleCssProperty(string $property, string $value, \DOMElement $node): bool
+    {
+        if (!isset($this->cssToHtmlMap[$property])) {
+            return false;
+        }
+
+        $mapping = $this->cssToHtmlMap[$property];
+        $nodesMatch = !isset($mapping['nodes']) || \in_array($node->nodeName, $mapping['nodes'], true);
+        $valuesMatch = !isset($mapping['values']) || \in_array($value, $mapping['values'], true);
+        $canBeMapped = $nodesMatch && $valuesMatch;
+        if ($canBeMapped) {
+            $node->setAttribute($mapping['attribute'], $value);
+        }
+
+        return $canBeMapped;
+    }
+
+    /**
+     * Maps CSS properties that need special transformation to an HTML attribute.
+     *
+     * @param string $property the name of the CSS property to map
+     * @param string $value the value of the style rule to map
+     * @param \DOMElement $node node to apply styles to
+     */
+    private function mapComplexCssProperty(string $property, string $value, \DOMElement $node): void
+    {
+        switch ($property) {
+            case 'background':
+                $this->mapBackgroundProperty($node, $value);
+                break;
+            case 'width':
+                // intentional fall-through
+            case 'height':
+                $this->mapWidthOrHeightProperty($node, $value, $property);
+                break;
+            case 'margin':
+                $this->mapMarginProperty($node, $value);
+                break;
+            case 'border':
+                $this->mapBorderProperty($node, $value);
+                break;
+            default:
+        }
+    }
+
+    /**
+     * @param \DOMElement $node node to apply styles to
+     * @param string $value the value of the style rule to map
+     */
+    private function mapBackgroundProperty(\DOMElement $node, string $value): void
+    {
+        // parse out the color, if any
+        /** @var array<int, string> $styles */
+        $styles = \explode(' ', $value, 2);
+        $first = $styles[0];
+        if (\is_numeric($first[0]) || \strncmp($first, 'url', 3) === 0) {
+            return;
+        }
+
+        // as this is not a position or image, assume it's a color
+        $node->setAttribute('bgcolor', $first);
+    }
+
+    /**
+     * @param \DOMElement $node node to apply styles to
+     * @param string $value the value of the style rule to map
+     * @param string $property the name of the CSS property to map
+     */
+    private function mapWidthOrHeightProperty(\DOMElement $node, string $value, string $property): void
+    {
+        $preg = new Preg();
+
+        // only parse values in px and %, but not values like "auto"
+        if ($preg->match('/^(\\d+)(\\.(\\d+))?(px|%)$/', $value) === 0) {
+            return;
+        }
+
+        $number = $preg->replace('/[^0-9.%]/', '', $value);
+        $node->setAttribute($property, $number);
+    }
+
+    /**
+     * @param \DOMElement $node node to apply styles to
+     * @param string $value the value of the style rule to map
+     */
+    private function mapMarginProperty(\DOMElement $node, string $value): void
+    {
+        if (!$this->isTableOrImageNode($node)) {
+            return;
+        }
+
+        $margins = $this->parseCssShorthandValue($value);
+        if ($margins['left'] === 'auto' && $margins['right'] === 'auto') {
+            $node->setAttribute('align', 'center');
+        }
+    }
+
+    /**
+     * @param \DOMElement $node node to apply styles to
+     * @param string $value the value of the style rule to map
+     */
+    private function mapBorderProperty(\DOMElement $node, string $value): void
+    {
+        if (!$this->isTableOrImageNode($node)) {
+            return;
+        }
+
+        if ($value === 'none' || $value === '0') {
+            $node->setAttribute('border', '0');
+        }
+    }
+
+    /**
+     * @param \DOMElement $node
+     *
+     * @return bool
+     */
+    private function isTableOrImageNode(\DOMElement $node): bool
+    {
+        return $node->nodeName === 'table' || $node->nodeName === 'img';
+    }
+
+    /**
+     * Parses a shorthand CSS value and splits it into individual values.  For example: `padding: 0 auto;` - `0 auto` is
+     * split into top: 0, left: auto, bottom: 0, right: auto.
+     *
+     * @param string $value a CSS property value with 1, 2, 3 or 4 sizes
+     *
+     * @return array<string, string>
+     *         an array of values for top, right, bottom and left (using these as associative array keys)
+     */
+    private function parseCssShorthandValue(string $value): array
+    {
+        $values = (new Preg())->split('/\\s+/', $value);
+
+        $css = [];
+        $css['top'] = $values[0];
+        $css['right'] = (\count($values) > 1) ? $values[1] : $css['top'];
+        $css['bottom'] = (\count($values) > 2) ? $values[2] : $css['top'];
+        $css['left'] = (\count($values) > 3) ? $values[3] : $css['right'];
+
+        return $css;
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssVariableEvaluator.php b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssVariableEvaluator.php
new file mode 100644
index 0000000..07c9a68
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/CssVariableEvaluator.php
@@ -0,0 +1,200 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\HtmlProcessor;
+
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\DeclarationBlockParser;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\Preg;
+
+/**
+ * This class can evaluate CSS custom properties that are defined and used in inline style attributes.
+ */
+final class CssVariableEvaluator extends AbstractHtmlProcessor
+{
+    /**
+     * temporary collection used by {@see replaceVariablesInDeclarations} and callee methods
+     *
+     * @var array<non-empty-string, string>
+     */
+    private $currentVariableDefinitions = [];
+
+    /**
+     * Replaces all CSS custom property references in inline style attributes with their corresponding values where
+     * defined in inline style attributes (either from the element itself or the nearest ancestor).
+     *
+     * @return $this
+     *
+     * @throws \UnexpectedValueException
+     */
+    public function evaluateVariables(): self
+    {
+        return $this->evaluateVariablesInElementAndDescendants($this->getHtmlElement(), []);
+    }
+
+    /**
+     * @param array<non-empty-string, string> $declarations
+     *
+     * @return array<non-empty-string, string>
+     */
+    private function getVariableDefinitionsFromDeclarations(array $declarations): array
+    {
+        return \array_filter(
+            $declarations,
+            static function (string $key): bool {
+                return \substr($key, 0, 2) === '--';
+            },
+            ARRAY_FILTER_USE_KEY
+        );
+    }
+
+    /**
+     * Callback function for {@see replaceVariablesInPropertyValue} performing regular expression replacement.
+     *
+     * @param array<int, string> $matches
+     */
+    private function getPropertyValueReplacement(array $matches): string
+    {
+        $variableName = $matches[1];
+
+        if (isset($this->currentVariableDefinitions[$variableName])) {
+            $variableValue = $this->currentVariableDefinitions[$variableName];
+        } else {
+            $fallbackValueSeparator = $matches[2] ?? '';
+            if ($fallbackValueSeparator !== '') {
+                $fallbackValue = $matches[3];
+                // The fallback value may use other CSS variables, so recurse
+                $variableValue = $this->replaceVariablesInPropertyValue($fallbackValue);
+            } else {
+                $variableValue = $matches[0];
+            }
+        }
+
+        return $variableValue;
+    }
+
+    /**
+     * Regular expression based on {@see https://stackoverflow.com/a/54143883/2511031 a StackOverflow answer}.
+     */
+    private function replaceVariablesInPropertyValue(string $propertyValue): string
+    {
+        return (new Preg())->replaceCallback(
+            '/
+                var\\(
+                    \\s*+
+                    # capture variable name including `--` prefix
+                    (
+                        --[^\\s\\),]++
+                    )
+                    \\s*+
+                    # capture optional fallback value
+                    (?:
+                        # capture separator to confirm there is a fallback value
+                        (,)\\s*
+                        # begin capture with named group that can be used recursively
+                        (?<recursable>
+                            # begin named group to match sequence without parentheses, except in strings
+                            (?<noparentheses>
+                                # repeated zero or more times:
+                                (?:
+                                    # sequence without parentheses or quotes
+                                    [^\\(\\)\'"]++
+                                    |
+                                    # string in double quotes
+                                    "(?>[^"\\\\]++|\\\\.)*"
+                                    |
+                                    # string in single quotes
+                                    \'(?>[^\'\\\\]++|\\\\.)*\'
+                                )*+
+                            )
+                            # repeated zero or more times:
+                            (?:
+                                # sequence in parentheses
+                                \\(
+                                    # using the named recursable pattern
+                                    (?&recursable)
+                                \\)
+                                # sequence without parentheses, except in strings
+                                (?&noparentheses)
+                            )*+
+                        )
+                    )?+
+                \\)
+            /x',
+            \Closure::fromCallable([$this, 'getPropertyValueReplacement']),
+            $propertyValue
+        );
+    }
+
+    /**
+     * @param array<non-empty-string, string> $declarations
+     *
+     * @return ?array<non-empty-string, string> `null` is returned if no substitutions were made.
+     */
+    private function replaceVariablesInDeclarations(array $declarations): ?array
+    {
+        $substitutionsMade = false;
+        $result = \array_map(
+            function (string $propertyValue) use (&$substitutionsMade): string {
+                $newPropertyValue = $this->replaceVariablesInPropertyValue($propertyValue);
+                if ($newPropertyValue !== $propertyValue) {
+                    $substitutionsMade = true;
+                }
+                return $newPropertyValue;
+            },
+            $declarations
+        );
+
+        return $substitutionsMade ? $result : null;
+    }
+
+    /**
+     * @param array<non-empty-string, string> $declarations
+     */
+    private function getDeclarationsAsString(array $declarations): string
+    {
+        $declarationStrings = \array_map(
+            static function (string $key, string $value): string {
+                return $key . ': ' . $value;
+            },
+            \array_keys($declarations),
+            \array_values($declarations)
+        );
+
+        return \implode('; ', $declarationStrings) . ';';
+    }
+
+    /**
+     * @param array<non-empty-string, string> $ancestorVariableDefinitions
+     *
+     * @return $this
+     */
+    private function evaluateVariablesInElementAndDescendants(
+        \DOMElement $element,
+        array $ancestorVariableDefinitions
+    ): self {
+        $style = $element->getAttribute('style');
+
+        // Avoid parsing declarations if none use or define a variable
+        if ((new Preg())->match('/(?<![\\w\\-])--[\\w\\-]/', $style) !== 0) {
+            $declarations = (new DeclarationBlockParser())->parse($style);
+            $variableDefinitions = $this->currentVariableDefinitions
+                = $this->getVariableDefinitionsFromDeclarations($declarations) + $ancestorVariableDefinitions;
+
+            $newDeclarations = $this->replaceVariablesInDeclarations($declarations);
+            if ($newDeclarations !== null) {
+                $element->setAttribute('style', $this->getDeclarationsAsString($newDeclarations));
+            }
+        } else {
+            $variableDefinitions = $ancestorVariableDefinitions;
+        }
+
+        foreach ($element->childNodes as $child) {
+            if ($child instanceof \DOMElement) {
+                $this->evaluateVariablesInElementAndDescendants($child, $variableDefinitions);
+            }
+        }
+
+        return $this;
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlNormalizer.php b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlNormalizer.php
new file mode 100644
index 0000000..3d9ecde
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlNormalizer.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\HtmlProcessor;
+
+/**
+ * Normalizes HTML:
+ * - add a document type (HTML5) if missing
+ * - disentangle incorrectly nested tags
+ * - add HEAD and BODY elements (if they are missing)
+ * - reformat the HTML
+ */
+final class HtmlNormalizer extends AbstractHtmlProcessor {}
diff --git a/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlPruner.php b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlPruner.php
new file mode 100644
index 0000000..814a7ed
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/HtmlProcessor/HtmlPruner.php
@@ -0,0 +1,141 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\HtmlProcessor;
+
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\CssInliner;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\ArrayIntersector;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities\Preg;
+
+/**
+ * This class can remove things from HTML.
+ */
+final class HtmlPruner extends AbstractHtmlProcessor
+{
+    /**
+     * We need to look for display:none, but we need to do a case-insensitive search. Since DOMDocument only
+     * supports XPath 1.0, lower-case() isn't available to us. We've thus far only set attributes to lowercase,
+     * not attribute values. Consequently, we need to translate() the letters that would be in 'NONE' ("NOE")
+     * to lowercase.
+     *
+     * @var string
+     */
+    private const DISPLAY_NONE_MATCHER
+        = '//*[@style and contains(translate(translate(@style," ",""),"NOE","noe"),"display:none")'
+        . ' and not(@class and contains(concat(" ", normalize-space(@class), " "), " -emogrifier-keep "))]';
+
+    /**
+     * Removes elements that have a "display: none;" style.
+     *
+     * @return $this
+     */
+    public function removeElementsWithDisplayNone(): self
+    {
+        $elementsWithStyleDisplayNone = $this->getXPath()->query(self::DISPLAY_NONE_MATCHER);
+        if ($elementsWithStyleDisplayNone->length === 0) {
+            return $this;
+        }
+
+        foreach ($elementsWithStyleDisplayNone as $element) {
+            $parentNode = $element->parentNode;
+            if ($parentNode !== null) {
+                $parentNode->removeChild($element);
+            }
+        }
+
+        return $this;
+    }
+
+    /**
+     * Removes classes that are no longer required (e.g. because there are no longer any CSS rules that reference them)
+     * from `class` attributes.
+     *
+     * Note that this does not inspect the CSS, but expects to be provided with a list of classes that are still in use.
+     *
+     * This method also has the (presumably beneficial) side-effect of minifying (removing superfluous whitespace from)
+     * `class` attributes.
+     *
+     * @param array<array-key, string> $classesToKeep names of classes that should not be removed
+     *
+     * @return $this
+     */
+    public function removeRedundantClasses(array $classesToKeep = []): self
+    {
+        $elementsWithClassAttribute = $this->getXPath()->query('//*[@class]');
+
+        if ($classesToKeep !== []) {
+            $this->removeClassesFromElements($elementsWithClassAttribute, $classesToKeep);
+        } else {
+            // Avoid unnecessary processing if there are no classes to keep.
+            $this->removeClassAttributeFromElements($elementsWithClassAttribute);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Removes classes from the `class` attribute of each element in `$elements`, except any in `$classesToKeep`,
+     * removing the `class` attribute itself if the resultant list is empty.
+     *
+     * @param \DOMNodeList $elements
+     * @param array<array-key, string> $classesToKeep
+     */
+    private function removeClassesFromElements(\DOMNodeList $elements, array $classesToKeep): void
+    {
+        $classesToKeepIntersector = new ArrayIntersector($classesToKeep);
+
+        $preg = new Preg();
+        /** @var \DOMElement $element */
+        foreach ($elements as $element) {
+            $elementClasses = $preg->split('/\\s++/', \trim($element->getAttribute('class')));
+            $elementClassesToKeep = $classesToKeepIntersector->intersectWith($elementClasses);
+            if ($elementClassesToKeep !== []) {
+                $element->setAttribute('class', \implode(' ', $elementClassesToKeep));
+            } else {
+                $element->removeAttribute('class');
+            }
+        }
+    }
+
+    /**
+     * Removes the `class` attribute from each element in `$elements`.
+     *
+     * @param \DOMNodeList $elements
+     */
+    private function removeClassAttributeFromElements(\DOMNodeList $elements): void
+    {
+        /** @var \DOMElement $element */
+        foreach ($elements as $element) {
+            $element->removeAttribute('class');
+        }
+    }
+
+    /**
+     * After CSS has been inlined, there will likely be some classes in `class` attributes that are no longer referenced
+     * by any remaining (uninlinable) CSS.  This method removes such classes.
+     *
+     * Note that it does not inspect the remaining CSS, but uses information readily available from the `CssInliner`
+     * instance about the CSS rules that could not be inlined.
+     *
+     * @param CssInliner $cssInliner object instance that performed the CSS inlining
+     *
+     * @return $this
+     *
+     * @throws \BadMethodCallException if `inlineCss` has not first been called on `$cssInliner`
+     */
+    public function removeRedundantClassesAfterCssInlined(CssInliner $cssInliner): self
+    {
+        $preg = new Preg();
+
+        $classesToKeepAsKeys = [];
+        foreach ($cssInliner->getMatchingUninlinableSelectors() as $selector) {
+            $preg->matchAll('/\\.(-?+[_a-zA-Z][\\w\\-]*+)/', $selector, $matches);
+            $classesToKeepAsKeys += \array_fill_keys($matches[1], true);
+        }
+
+        $this->removeRedundantClasses(\array_keys($classesToKeepAsKeys));
+
+        return $this;
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/Utilities/ArrayIntersector.php b/includes/Dependencies/Pelago/Emogrifier/Utilities/ArrayIntersector.php
new file mode 100644
index 0000000..fca404d
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Utilities/ArrayIntersector.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities;
+
+/**
+ * When computing many array intersections using the same array, it is more efficient to use `array_flip()` first and
+ * then `array_intersect_key()`, than `array_intersect()`.  See the discussion at
+ * {@link https://stackoverflow.com/questions/6329211/php-array-intersect-efficiency Stack Overflow} for more
+ * information.
+ *
+ * Of course, this is only possible if the arrays contain integer or string values, and either don't contain duplicates,
+ * or that fact that duplicates will be removed does not matter.
+ *
+ * This class takes care of the detail.
+ *
+ * @internal
+ */
+final class ArrayIntersector
+{
+    /**
+     * the array with which the object was constructed, with all its keys exchanged with their associated values
+     *
+     * @var array<array-key, array-key>
+     */
+    private $invertedArray;
+
+    /**
+     * Constructs the object with the array that will be reused for many intersection computations.
+     *
+     * @param array<array-key, array-key> $array
+     */
+    public function __construct(array $array)
+    {
+        $this->invertedArray = \array_flip($array);
+    }
+
+    /**
+     * Computes the intersection of `$array` and the array with which this object was constructed.
+     *
+     * @param array<array-key, array-key> $array
+     *
+     * @return array<array-key, array-key>
+     *         Returns an array containing all of the values in `$array` whose values exist in the array
+     *         with which this object was constructed.  Note that keys are preserved, order is maintained, but
+     *         duplicates are removed.
+     */
+    public function intersectWith(array $array): array
+    {
+        $invertedArray = \array_flip($array);
+
+        $invertedIntersection = \array_intersect_key($invertedArray, $this->invertedArray);
+
+        return \array_flip($invertedIntersection);
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/Utilities/CssConcatenator.php b/includes/Dependencies/Pelago/Emogrifier/Utilities/CssConcatenator.php
new file mode 100644
index 0000000..42544ad
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Utilities/CssConcatenator.php
@@ -0,0 +1,181 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities;
+
+/**
+ * Facilitates building a CSS string by appending rule blocks one at a time, checking whether the media query,
+ * selectors, or declarations block are the same as those from the preceding block and combining blocks in such cases.
+ *
+ * Example:
+ *  $concatenator = new CssConcatenator();
+ *  $concatenator->append(['body'], 'color: blue;');
+ *  $concatenator->append(['body'], 'font-size: 16px;');
+ *  $concatenator->append(['p'], 'margin: 1em 0;');
+ *  $concatenator->append(['ul', 'ol'], 'margin: 1em 0;');
+ *  $concatenator->append(['body'], 'font-size: 14px;', '@media screen and (max-width: 400px)');
+ *  $concatenator->append(['ul', 'ol'], 'margin: 0.75em 0;', '@media screen and (max-width: 400px)');
+ *  $css = $concatenator->getCss();
+ *
+ * `$css` (if unminified) would contain the following CSS:
+ * ` body {
+ * `   color: blue;
+ * `   font-size: 16px;
+ * ` }
+ * ` p, ul, ol {
+ * `   margin: 1em 0;
+ * ` }
+ * ` @media screen and (max-width: 400px) {
+ * `   body {
+ * `     font-size: 14px;
+ * `   }
+ * `   ul, ol {
+ * `     margin: 0.75em 0;
+ * `   }
+ * ` }
+ *
+ * @internal
+ */
+final class CssConcatenator
+{
+    /**
+     * Array of media rules in order.  Each element is an object with the following properties:
+     * - string `media` - The media query string, e.g. "@media screen and (max-width:639px)", or an empty string for
+     *   rules not within a media query block;
+     * - object[] `ruleBlocks` - Array of rule blocks in order, where each element is an object with the following
+     *   properties:
+     *   - mixed[] `selectorsAsKeys` - Array whose keys are selectors for the rule block (values are of no
+     *     significance);
+     *   - string `declarationsBlock` - The property declarations, e.g. "margin-top: 0.5em; padding: 0".
+     *
+     * @var array<int, object{
+     *   media: string,
+     *   ruleBlocks: array<int, object{
+     *     selectorsAsKeys: array<string, array-key>,
+     *     declarationsBlock: string
+     *   }>
+     * }>
+     */
+    private $mediaRules = [];
+
+    /**
+     * Appends a declaration block to the CSS.
+     *
+     * @param array<array-key, string> $selectors
+     *        array of selectors for the rule, e.g. ["ul", "ol", "p:first-child"]
+     * @param string $declarationsBlock
+     *        the property declarations, e.g. "margin-top: 0.5em; padding: 0"
+     * @param string $media
+     *        the media query for the rule, e.g. "@media screen and (max-width:639px)", or an empty string if none
+     */
+    public function append(array $selectors, string $declarationsBlock, string $media = ''): void
+    {
+        $selectorsAsKeys = \array_flip($selectors);
+
+        $mediaRule = $this->getOrCreateMediaRuleToAppendTo($media);
+        $ruleBlocks = $mediaRule->ruleBlocks;
+        $lastRuleBlock = \end($ruleBlocks);
+
+        $hasSameDeclarationsAsLastRule = \is_object($lastRuleBlock)
+            && $declarationsBlock === $lastRuleBlock->declarationsBlock;
+        if ($hasSameDeclarationsAsLastRule) {
+            $lastRuleBlock->selectorsAsKeys += $selectorsAsKeys;
+        } else {
+            $lastRuleBlockSelectors = \is_object($lastRuleBlock) ? $lastRuleBlock->selectorsAsKeys : [];
+            $hasSameSelectorsAsLastRule = \is_object($lastRuleBlock)
+                && self::hasEquivalentSelectors($selectorsAsKeys, $lastRuleBlockSelectors);
+            if ($hasSameSelectorsAsLastRule) {
+                $lastDeclarationsBlockWithoutSemicolon = \rtrim(\rtrim($lastRuleBlock->declarationsBlock), ';');
+                $lastRuleBlock->declarationsBlock = $lastDeclarationsBlockWithoutSemicolon . ';' . $declarationsBlock;
+            } else {
+                $mediaRule->ruleBlocks[] = (object) \compact('selectorsAsKeys', 'declarationsBlock');
+            }
+        }
+    }
+
+    /**
+     * @return string
+     */
+    public function getCss(): string
+    {
+        return \implode('', \array_map([self::class, 'getMediaRuleCss'], $this->mediaRules));
+    }
+
+    /**
+     * @param string $media The media query for rules to be appended, e.g. "@media screen and (max-width:639px)",
+     *        or an empty string if none.
+     *
+     * @return object{
+     *           media: string,
+     *           ruleBlocks: array<int, object{
+     *             selectorsAsKeys: array<string, array-key>,
+     *             declarationsBlock: string
+     *           }>
+     *         }
+     */
+    private function getOrCreateMediaRuleToAppendTo(string $media): object
+    {
+        $lastMediaRule = \end($this->mediaRules);
+        if (\is_object($lastMediaRule) && $media === $lastMediaRule->media) {
+            return $lastMediaRule;
+        }
+
+        $newMediaRule = (object) [
+            'media' => $media,
+            'ruleBlocks' => [],
+        ];
+        $this->mediaRules[] = $newMediaRule;
+        return $newMediaRule;
+    }
+
+    /**
+     * Tests if two sets of selectors are equivalent (i.e. the same selectors, possibly in a different order).
+     *
+     * @param array<string, array-key> $selectorsAsKeys1
+     *        array in which the selectors are the keys, and the values are of no significance
+     * @param array<string, array-key> $selectorsAsKeys2 another such array
+     *
+     * @return bool
+     */
+    private static function hasEquivalentSelectors(array $selectorsAsKeys1, array $selectorsAsKeys2): bool
+    {
+        return \count($selectorsAsKeys1) === \count($selectorsAsKeys2)
+            && \count($selectorsAsKeys1) === \count($selectorsAsKeys1 + $selectorsAsKeys2);
+    }
+
+    /**
+     * @param object{
+     *          media: string,
+     *          ruleBlocks: array<int, object{
+     *            selectorsAsKeys: array<string, array-key>,
+     *            declarationsBlock: string
+     *          }>
+     *        } $mediaRule
+     *
+     * @return string CSS for the media rule.
+     */
+    private static function getMediaRuleCss(object $mediaRule): string
+    {
+        $ruleBlocks = $mediaRule->ruleBlocks;
+        $css = \implode('', \array_map([self::class, 'getRuleBlockCss'], $ruleBlocks));
+        $media = $mediaRule->media;
+        if ($media !== '') {
+            $css = $media . '{' . $css . '}';
+        }
+        return $css;
+    }
+
+    /**
+     * @param object{selectorsAsKeys: array<string, array-key>, declarationsBlock: string} $ruleBlock
+     *
+     * @return string CSS for the rule block.
+     */
+    private static function getRuleBlockCss(object $ruleBlock): string
+    {
+        $selectorsAsKeys = $ruleBlock->selectorsAsKeys;
+        $selectors = \array_keys($selectorsAsKeys);
+        $declarationsBlock = $ruleBlock->declarationsBlock;
+        return \implode(',', $selectors) . '{' . $declarationsBlock . '}';
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/Utilities/DeclarationBlockParser.php b/includes/Dependencies/Pelago/Emogrifier/Utilities/DeclarationBlockParser.php
new file mode 100644
index 0000000..d645e2a
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Utilities/DeclarationBlockParser.php
@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities;
+
+/**
+ * Provides a common method for parsing CSS declaration blocks.
+ * These might be from actual CSS, or from the `style` attribute of an HTML DOM element.
+ *
+ * Caches results globally.
+ *
+ * @internal
+ */
+final class DeclarationBlockParser
+{
+    /**
+     * @var array<string, array<non-empty-string, string>>
+     */
+    private static $cache = [];
+
+    /**
+     * CSS custom properties (variables) have case-sensitive names, so their case must be preserved.
+     * Standard CSS properties have case-insensitive names, which are converted to lowercase.
+     *
+     * @param non-empty-string $name
+     *
+     * @return non-empty-string
+     */
+    public function normalizePropertyName(string $name): string
+    {
+        if (\substr($name, 0, 2) === '--') {
+            return $name;
+        } else {
+            return \strtolower($name);
+        }
+    }
+
+    /**
+     * Parses a CSS declaration block into property name/value pairs.
+     *
+     * Example:
+     *
+     * The declaration block
+     *
+     *   "color: #000; font-weight: bold;"
+     *
+     * will be parsed into the following array:
+     *
+     *   "color" => "#000"
+     *   "font-weight" => "bold"
+     *
+     * @param string $declarationBlock the CSS declarations block without the curly braces, may be empty
+     *
+     * @return array<non-empty-string, string>
+     *         the CSS declarations with the property names as array keys and the property values as array values
+     *
+     * @throws \UnexpectedValueException if an empty property name is encountered (which cannot happen)
+     */
+    public function parse(string $declarationBlock): array
+    {
+        if (isset(self::$cache[$declarationBlock])) {
+            return self::$cache[$declarationBlock];
+        }
+
+        $preg = new Preg();
+
+        $declarations = $preg->split('/;(?!base64|charset)/', $declarationBlock);
+
+        $properties = [];
+        foreach ($declarations as $declaration) {
+            $matches = [];
+            if (
+                $preg->match(
+                    '/^([A-Za-z\\-]+)\\s*:\\s*(.+)$/s',
+                    \trim($declaration),
+                    $matches
+                )
+                === 0
+            ) {
+                continue;
+            }
+
+            $propertyName = $matches[1];
+            if ($propertyName === '') {
+                // This cannot happen since the regular epression matches one or more characters.
+                throw new \UnexpectedValueException('An empty property name was encountered.', 1727046409);
+            }
+            $propertyValue = $matches[2];
+            $properties[$this->normalizePropertyName($propertyName)] = $propertyValue;
+        }
+        self::$cache[$declarationBlock] = $properties;
+
+        return $properties;
+    }
+}
diff --git a/includes/Dependencies/Pelago/Emogrifier/Utilities/Preg.php b/includes/Dependencies/Pelago/Emogrifier/Utilities/Preg.php
new file mode 100644
index 0000000..76b7b20
--- /dev/null
+++ b/includes/Dependencies/Pelago/Emogrifier/Utilities/Preg.php
@@ -0,0 +1,202 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\Utilities;
+
+/**
+ * PHP's `preg_*` functions can return `false` on failure.
+ * Failure is rare but may occur with a complex pattern applied to a long subject.
+ * Catastrophic backtracking may occur ({@see https://www.regular-expressions.info/catastrophic.html}).
+ * Failure may also occur due to programmer error, if an invalid pattern is provided.
+ *
+ * Catering for failure in each case clutters up the code with error handling.
+ * This class provides wrappers for some `preg_*` functions, with errors handled either
+ * - by throwing an exception, or
+ * - by triggering a user error and providing fallback logic (e.g. returning the subject string unmodified).
+ *
+ * @internal
+ */
+final class Preg
+{
+    /**
+     * whether to throw exceptions on errors (or call `trigger_error` and implement fallback)
+     *
+     * @var bool
+     */
+    private $throwExceptions = false;
+
+    /**
+     * Sets whether exceptions should be thrown if an error occurs.
+     */
+    public function throwExceptions(bool $throw): self
+    {
+        $this->throwExceptions = $throw;
+
+        return $this;
+    }
+
+    /**
+     * Wraps `preg_replace`, though does not support `$subject` being an array.
+     * If an error occurs, and exceptions are not being thrown, the original `$subject` is returned.
+     *
+     * @param non-empty-string|non-empty-array<non-empty-string> $pattern
+     * @param string|non-empty-array<string> $replacement
+     *
+     * @throws \RuntimeException
+     */
+    public function replace($pattern, $replacement, string $subject, int $limit = -1, ?int &$count = null): string
+    {
+        $result = \preg_replace($pattern, $replacement, $subject, $limit, $count);
+
+        if ($result === null) {
+            $this->logOrThrowPregLastError();
+            $result = $subject;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Wraps `preg_replace_callback`, though does not support `$subject` being an array.
+     * If an error occurs, and exceptions are not being thrown, the original `$subject` is returned.
+     *
+     * Note that (unlike when calling `preg_replace_callback`), `$callback` cannot be a non-public method
+     * represented by an array comprising an object or class name and the method name.
+     * To circumvent that, use `\Closure::fromCallable([$objectOrClassName, 'method'])`.
+     *
+     * @param non-empty-string|non-empty-array<non-empty-string> $pattern
+     *
+     * @throws \RuntimeException
+     */
+    public function replaceCallback(
+        $pattern,
+        callable $callback,
+        string $subject,
+        int $limit = -1,
+        ?int &$count = null
+    ): string {
+        $result = \preg_replace_callback($pattern, $callback, $subject, $limit, $count);
+
+        if ($result === null) {
+            $this->logOrThrowPregLastError();
+            $result = $subject;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Wraps `preg_split`.
+     * If an error occurs, and exceptions are not being thrown,
+     * a single-element array containing the original `$subject` is returned.
+     * This method does not support the `PREG_SPLIT_OFFSET_CAPTURE` flag and will throw an exception if it is specified.
+     *
+     * @param non-empty-string $pattern
+     *
+     * @return array<int, string>
+     *
+     * @throws \RuntimeException
+     */
+    public function split(string $pattern, string $subject, int $limit = -1, int $flags = 0): array
+    {
+        if (($flags & PREG_SPLIT_OFFSET_CAPTURE) !== 0) {
+            throw new \RuntimeException('PREG_SPLIT_OFFSET_CAPTURE is not supported by Preg::split', 1726506348);
+        }
+
+        $result = \preg_split($pattern, $subject, $limit, $flags);
+
+        if ($result === false) {
+            $this->logOrThrowPregLastError();
+            $result = [$subject];
+        }
+
+        return $result;
+    }
+
+    /**
+     * Wraps `preg_match`.
+     * If an error occurs, and exceptions are not being thrown,
+     * zero (`0`) is returned, and if the `$matches` parameter is provided, it is set to an empty array.
+     * This method does not currently support the `$flags` or `$offset` parameters.
+     *
+     * @param non-empty-string $pattern
+     * @param array<int, string> $matches
+     *
+     * @return 0|1
+     *
+     * @throws \RuntimeException
+     */
+    public function match(string $pattern, string $subject, ?array &$matches = null): int
+    {
+        $result = \preg_match($pattern, $subject, $matches);
+
+        if ($result === false) {
+            $this->logOrThrowPregLastError();
+            $result = 0;
+            $matches = [];
+        }
+
+        return $result;
+    }
+
+    /**
+     * Wraps `preg_match_all`.
+     *
+     * If an error occurs, and exceptions are not being thrown, zero (`0`) is returned.
+     *
+     * In the error case, if the `$matches` parameter is provided, it is set to an array containing empty arrays for the
+     * full pattern match and any possible subpattern match that might be expected.
+     * The algorithm to determine the length of this array simply counts the number of opening parentheses in the
+     * `$pattern`, which may result in a longer array than expected, but guarantees that it is at least as long as
+     * expected.
+     *
+     * This method does not currently support the `$flags` or `$offset` parameters.
+     *
+     * @param non-empty-string $pattern
+     * @param array<int, array<int, string>> $matches
+     *
+     * @throws \RuntimeException
+     */
+    public function matchAll(string $pattern, string $subject, ?array &$matches = null): int
+    {
+        $result = \preg_match_all($pattern, $subject, $matches);
+
+        if ($result === false) {
+            $this->logOrThrowPregLastError();
+            $result = 0;
+            $matches = \array_fill(0, \substr_count($pattern, '(') + 1, []);
+        }
+
+        return $result;
+    }
+
+    /**
+     * Obtains the name of the error constant for `preg_last_error`
+     * (based on code posted at {@see https://www.php.net/manual/en/function.preg-last-error.php#124124})
+     * and puts it into an error message which is either passed to `trigger_error`
+     * or used in the exception which is thrown (depending on the `$throwExceptions` property).
+     *
+     * @throws \RuntimeException
+     */
+    private function logOrThrowPregLastError(): void
+    {
+        $pcreConstants = \get_defined_constants(true)['pcre'];
+        $pcreErrorConstantNames = \array_flip(\array_filter(
+            $pcreConstants,
+            static function (string $key): bool {
+                return \substr($key, -6) === '_ERROR';
+            },
+            ARRAY_FILTER_USE_KEY
+        ));
+
+        $pregLastError = \preg_last_error();
+        $message = 'PCRE regex execution error `' . (string) ($pcreErrorConstantNames[$pregLastError] ?? $pregLastError)
+            . '`';
+
+        if ($this->throwExceptions) {
+            throw new \RuntimeException($message, 1592870147);
+        }
+        \trigger_error($message);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSElement.php b/includes/Dependencies/Sabberworm/CSS/CSSElement.php
new file mode 100644
index 0000000..f707989
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSElement.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS;
+
+/**
+ * Represents any entity in the CSS that is encapsulated by a class.
+ *
+ * Its primary purpose is to provide a type for use with `Document::getAllValues()`
+ * when a subset of values from a particular part of the document is required.
+ *
+ * Thus, elements which don't contain `Value`s (such as statement at-rules) don't need to implement this.
+ *
+ * It extends `Renderable` because every element is renderable.
+ */
+interface CSSElement extends Renderable {}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSList/AtRuleBlockList.php b/includes/Dependencies/Sabberworm/CSS/CSSList/AtRuleBlockList.php
new file mode 100644
index 0000000..1190be1
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSList/AtRuleBlockList.php
@@ -0,0 +1,72 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\AtRule;
+
+/**
+ * A `BlockList` constructed by an unknown at-rule. `@media` rules are rendered into `AtRuleBlockList` objects.
+ */
+class AtRuleBlockList extends CSSBlockList implements AtRule
+{
+    /**
+     * @var non-empty-string
+     */
+    private $type;
+
+    /**
+     * @var string
+     */
+    private $arguments;
+
+    /**
+     * @param non-empty-string $type
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $type, string $arguments = '', ?int $lineNumber = null)
+    {
+        parent::__construct($lineNumber);
+        $this->type = $type;
+        $this->arguments = $arguments;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string
+    {
+        return $this->type;
+    }
+
+    public function atRuleArgs(): string
+    {
+        return $this->arguments;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $formatter = $outputFormat->getFormatter();
+        $result = $formatter->comments($this);
+        $result .= $outputFormat->getContentBeforeAtRuleBlock();
+        $arguments = $this->arguments;
+        if ($arguments !== '') {
+            $arguments = ' ' . $arguments;
+        }
+        $result .= "@{$this->type}$arguments{$formatter->spaceBeforeOpeningBrace()}{";
+        $result .= $this->renderListContents($outputFormat);
+        $result .= '}';
+        $result .= $outputFormat->getContentAfterAtRuleBlock();
+        return $result;
+    }
+
+    public function isRootList(): bool
+    {
+        return false;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSList/CSSBlockList.php b/includes/Dependencies/Sabberworm/CSS/CSSList/CSSBlockList.php
new file mode 100644
index 0000000..20fca42
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSList/CSSBlockList.php
@@ -0,0 +1,184 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSElement;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Rule\Rule;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\DeclarationBlock;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\RuleContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\RuleSet;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\CSSFunction;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\Value;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\ValueList;
+
+/**
+ * A `CSSBlockList` is a `CSSList` whose `DeclarationBlock`s are guaranteed to contain valid declaration blocks or
+ * at-rules.
+ *
+ * Most `CSSList`s conform to this category but some at-rules (such as `@keyframes`) do not.
+ */
+abstract class CSSBlockList extends CSSList
+{
+    /**
+     * Gets all `DeclarationBlock` objects recursively, no matter how deeply nested the selectors are.
+     *
+     * @return list<DeclarationBlock>
+     */
+    public function getAllDeclarationBlocks(): array
+    {
+        $result = [];
+
+        foreach ($this->contents as $item) {
+            if ($item instanceof DeclarationBlock) {
+                $result[] = $item;
+            } elseif ($item instanceof CSSBlockList) {
+                $result = \array_merge($result, $item->getAllDeclarationBlocks());
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * Returns all `RuleSet` objects recursively found in the tree, no matter how deeply nested the rule sets are.
+     *
+     * @return list<RuleSet>
+     */
+    public function getAllRuleSets(): array
+    {
+        $result = [];
+
+        foreach ($this->contents as $item) {
+            if ($item instanceof RuleSet) {
+                $result[] = $item;
+            } elseif ($item instanceof CSSBlockList) {
+                $result = \array_merge($result, $item->getAllRuleSets());
+            } elseif ($item instanceof DeclarationBlock) {
+                $result[] = $item->getRuleSet();
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * Returns all `Value` objects found recursively in `Rule`s in the tree.
+     *
+     * @param CSSElement|null $element
+     *        This is the `CSSList` or `RuleSet` to start the search from (defaults to the whole document).
+     * @param string|null $ruleSearchPattern
+     *        This allows filtering rules by property name
+     *        (e.g. if "color" is passed, only `Value`s from `color` properties will be returned,
+     *        or if "font-" is provided, `Value`s from all font rules, like `font-size`, and including `font` itself,
+     *        will be returned).
+     * @param bool $searchInFunctionArguments whether to also return `Value` objects used as `CSSFunction` arguments.
+     *
+     * @return list<Value>
+     *
+     * @see RuleSet->getRules()
+     */
+    public function getAllValues(
+        ?CSSElement $element = null,
+        ?string $ruleSearchPattern = null,
+        bool $searchInFunctionArguments = false
+    ): array {
+        $element = $element ?? $this;
+
+        $result = [];
+        if ($element instanceof CSSBlockList) {
+            foreach ($element->getContents() as $contentItem) {
+                // Statement at-rules are skipped since they do not contain values.
+                if ($contentItem instanceof CSSElement) {
+                    $result = \array_merge(
+                        $result,
+                        $this->getAllValues($contentItem, $ruleSearchPattern, $searchInFunctionArguments)
+                    );
+                }
+            }
+        } elseif ($element instanceof RuleContainer) {
+            foreach ($element->getRules($ruleSearchPattern) as $rule) {
+                $result = \array_merge(
+                    $result,
+                    $this->getAllValues($rule, $ruleSearchPattern, $searchInFunctionArguments)
+                );
+            }
+        } elseif ($element instanceof Rule) {
+            $value = $element->getValue();
+            // `string` values are discarded.
+            if ($value instanceof CSSElement) {
+                $result = \array_merge(
+                    $result,
+                    $this->getAllValues($value, $ruleSearchPattern, $searchInFunctionArguments)
+                );
+            }
+        } elseif ($element instanceof ValueList) {
+            if ($searchInFunctionArguments || !($element instanceof CSSFunction)) {
+                foreach ($element->getListComponents() as $component) {
+                    // `string` components are discarded.
+                    if ($component instanceof CSSElement) {
+                        $result = \array_merge(
+                            $result,
+                            $this->getAllValues($component, $ruleSearchPattern, $searchInFunctionArguments)
+                        );
+                    }
+                }
+            }
+        } elseif ($element instanceof Value) {
+            $result[] = $element;
+        }
+
+        return $result;
+    }
+
+    /**
+     * @return list<Selector>
+     */
+    protected function getAllSelectors(?string $specificitySearch = null): array
+    {
+        $result = [];
+
+        foreach ($this->getAllDeclarationBlocks() as $declarationBlock) {
+            foreach ($declarationBlock->getSelectors() as $selector) {
+                if ($specificitySearch === null) {
+                    $result[] = $selector;
+                } else {
+                    $comparator = '===';
+                    $expressionParts = \explode(' ', $specificitySearch);
+                    $targetSpecificity = $expressionParts[0];
+                    if (\count($expressionParts) > 1) {
+                        $comparator = $expressionParts[0];
+                        $targetSpecificity = $expressionParts[1];
+                    }
+                    $targetSpecificity = (int) $targetSpecificity;
+                    $selectorSpecificity = $selector->getSpecificity();
+                    $comparatorMatched = false;
+                    switch ($comparator) {
+                        case '<=':
+                            $comparatorMatched = $selectorSpecificity <= $targetSpecificity;
+                            break;
+                        case '<':
+                            $comparatorMatched = $selectorSpecificity < $targetSpecificity;
+                            break;
+                        case '>=':
+                            $comparatorMatched = $selectorSpecificity >= $targetSpecificity;
+                            break;
+                        case '>':
+                            $comparatorMatched = $selectorSpecificity > $targetSpecificity;
+                            break;
+                        default:
+                            $comparatorMatched = $selectorSpecificity === $targetSpecificity;
+                            break;
+                    }
+                    if ($comparatorMatched) {
+                        $result[] = $selector;
+                    }
+                }
+            }
+        }
+
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSList/CSSList.php b/includes/Dependencies/Sabberworm/CSS/CSSList/CSSList.php
new file mode 100644
index 0000000..5488c85
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSList/CSSList.php
@@ -0,0 +1,428 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSElement;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\AtRule;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Charset;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\CSSNamespace;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Import;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\AtRuleSet;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\DeclarationBlock;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet\RuleSet;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\CSSString;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\URL;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\Value;
+
+/**
+ * This is the most generic container available. It can contain `DeclarationBlock`s (rule sets with a selector),
+ * `RuleSet`s as well as other `CSSList` objects.
+ *
+ * It can also contain `Import` and `Charset` objects stemming from at-rules.
+ *
+ * Note that `CSSListItem` extends both `Commentable` and `Renderable`,
+ * so those interfaces must also be implemented by concrete subclasses.
+ */
+abstract class CSSList implements CSSElement, CSSListItem, Positionable
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * @var array<int<0, max>, CSSListItem>
+     *
+     * @internal since 8.8.0
+     */
+    protected $contents = [];
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(?int $lineNumber = null)
+    {
+        $this->setPosition($lineNumber);
+    }
+
+    /**
+     * @throws UnexpectedTokenException
+     * @throws SourceException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parseList(ParserState $parserState, CSSList $list): void
+    {
+        $isRoot = $list instanceof Document;
+        $usesLenientParsing = $parserState->getSettings()->usesLenientParsing();
+        $comments = [];
+        while (!$parserState->isEnd()) {
+            $comments = \array_merge($comments, $parserState->consumeWhiteSpace());
+            $listItem = null;
+            if ($usesLenientParsing) {
+                try {
+                    $listItem = self::parseListItem($parserState, $list);
+                } catch (UnexpectedTokenException $e) {
+                    $listItem = false;
+                }
+            } else {
+                $listItem = self::parseListItem($parserState, $list);
+            }
+            if ($listItem === null) {
+                // List parsing finished
+                return;
+            }
+            if ($listItem) {
+                $listItem->addComments($comments);
+                $list->append($listItem);
+            }
+            $comments = $parserState->consumeWhiteSpace();
+        }
+        $list->addComments($comments);
+        if (!$isRoot && !$usesLenientParsing) {
+            throw new SourceException('Unexpected end of document', $parserState->currentLine());
+        }
+    }
+
+    /**
+     * @return CSSListItem|false|null
+     *         If `null` is returned, it means the end of the list has been reached.
+     *         If `false` is returned, it means an invalid item has been encountered,
+     *         but parsing of the next item should proceed.
+     *
+     * @throws SourceException
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseListItem(ParserState $parserState, CSSList $list)
+    {
+        $isRoot = $list instanceof Document;
+        if ($parserState->comes('@')) {
+            $atRule = self::parseAtRule($parserState);
+            if ($atRule instanceof Charset) {
+                if (!$isRoot) {
+                    throw new UnexpectedTokenException(
+                        '@charset may only occur in root document',
+                        '',
+                        'custom',
+                        $parserState->currentLine()
+                    );
+                }
+                if (\count($list->getContents()) > 0) {
+                    throw new UnexpectedTokenException(
+                        '@charset must be the first parseable token in a document',
+                        '',
+                        'custom',
+                        $parserState->currentLine()
+                    );
+                }
+                $parserState->setCharset($atRule->getCharset());
+            }
+            return $atRule;
+        } elseif ($parserState->comes('}')) {
+            if ($isRoot) {
+                if ($parserState->getSettings()->usesLenientParsing()) {
+                    return DeclarationBlock::parse($parserState) ?? false;
+                } else {
+                    throw new SourceException('Unopened {', $parserState->currentLine());
+                }
+            } else {
+                // End of list
+                return null;
+            }
+        } else {
+            return DeclarationBlock::parse($parserState, $list) ?? false;
+        }
+    }
+
+    /**
+     * @throws SourceException
+     * @throws UnexpectedTokenException
+     * @throws UnexpectedEOFException
+     */
+    private static function parseAtRule(ParserState $parserState): ?CSSListItem
+    {
+        $parserState->consume('@');
+        $identifier = $parserState->parseIdentifier();
+        $identifierLineNumber = $parserState->currentLine();
+        $parserState->consumeWhiteSpace();
+        if ($identifier === 'import') {
+            $location = URL::parse($parserState);
+            $parserState->consumeWhiteSpace();
+            $mediaQuery = null;
+            if (!$parserState->comes(';')) {
+                $mediaQuery = \trim($parserState->consumeUntil([';', ParserState::EOF]));
+                if ($mediaQuery === '') {
+                    $mediaQuery = null;
+                }
+            }
+            $parserState->consumeUntil([';', ParserState::EOF], true, true);
+            return new Import($location, $mediaQuery, $identifierLineNumber);
+        } elseif ($identifier === 'charset') {
+            $charsetString = CSSString::parse($parserState);
+            $parserState->consumeWhiteSpace();
+            $parserState->consumeUntil([';', ParserState::EOF], true, true);
+            return new Charset($charsetString, $identifierLineNumber);
+        } elseif (self::identifierIs($identifier, 'keyframes')) {
+            $result = new KeyFrame($identifierLineNumber);
+            $result->setVendorKeyFrame($identifier);
+            $result->setAnimationName(\trim($parserState->consumeUntil('{', false, true)));
+            CSSList::parseList($parserState, $result);
+            if ($parserState->comes('}')) {
+                $parserState->consume('}');
+            }
+            return $result;
+        } elseif ($identifier === 'namespace') {
+            $prefix = null;
+            $url = Value::parsePrimitiveValue($parserState);
+            if (!$parserState->comes(';')) {
+                $prefix = $url;
+                $url = Value::parsePrimitiveValue($parserState);
+            }
+            $parserState->consumeUntil([';', ParserState::EOF], true, true);
+            if ($prefix !== null && !\is_string($prefix)) {
+                throw new UnexpectedTokenException('Wrong namespace prefix', $prefix, 'custom', $identifierLineNumber);
+            }
+            if (!($url instanceof CSSString || $url instanceof URL)) {
+                throw new UnexpectedTokenException(
+                    'Wrong namespace url of invalid type',
+                    $url,
+                    'custom',
+                    $identifierLineNumber
+                );
+            }
+            return new CSSNamespace($url, $prefix, $identifierLineNumber);
+        } else {
+            // Unknown other at rule (font-face or such)
+            $arguments = \trim($parserState->consumeUntil('{', false, true));
+            if (\substr_count($arguments, '(') !== \substr_count($arguments, ')')) {
+                if ($parserState->getSettings()->usesLenientParsing()) {
+                    return null;
+                } else {
+                    throw new SourceException('Unmatched brace count in media query', $parserState->currentLine());
+                }
+            }
+            $useRuleSet = true;
+            foreach (\explode('/', AtRule::BLOCK_RULES) as $blockRuleName) {
+                if (self::identifierIs($identifier, $blockRuleName)) {
+                    $useRuleSet = false;
+                    break;
+                }
+            }
+            if ($useRuleSet) {
+                $atRule = new AtRuleSet($identifier, $arguments, $identifierLineNumber);
+                RuleSet::parseRuleSet($parserState, $atRule);
+            } else {
+                $atRule = new AtRuleBlockList($identifier, $arguments, $identifierLineNumber);
+                CSSList::parseList($parserState, $atRule);
+                if ($parserState->comes('}')) {
+                    $parserState->consume('}');
+                }
+            }
+            return $atRule;
+        }
+    }
+
+    /**
+     * Tests an identifier for a given value. Since identifiers are all keywords, they can be vendor-prefixed.
+     * We need to check for these versions too.
+     */
+    private static function identifierIs(string $identifier, string $match): bool
+    {
+        if (\strcasecmp($identifier, $match) === 0) {
+            return true;
+        }
+
+        return \preg_match("/^(-\\w+-)?$match$/i", $identifier) === 1;
+    }
+
+    /**
+     * Prepends an item to the list of contents.
+     */
+    public function prepend(CSSListItem $item): void
+    {
+        \array_unshift($this->contents, $item);
+    }
+
+    /**
+     * Appends an item to the list of contents.
+     */
+    public function append(CSSListItem $item): void
+    {
+        $this->contents[] = $item;
+    }
+
+    /**
+     * Splices the list of contents.
+     *
+     * @param array<int, CSSListItem> $replacement
+     */
+    public function splice(int $offset, ?int $length = null, ?array $replacement = null): void
+    {
+        \array_splice($this->contents, $offset, $length, $replacement);
+    }
+
+    /**
+     * Inserts an item in the CSS list before its sibling. If the desired sibling cannot be found,
+     * the item is appended at the end.
+     */
+    public function insertBefore(CSSListItem $item, CSSListItem $sibling): void
+    {
+        if (\in_array($sibling, $this->contents, true)) {
+            $this->replace($sibling, [$item, $sibling]);
+        } else {
+            $this->append($item);
+        }
+    }
+
+    /**
+     * Removes an item from the CSS list.
+     *
+     * @param CSSListItem $itemToRemove
+     *        May be a `RuleSet` (most likely a `DeclarationBlock`), an `Import`,
+     *        a `Charset` or another `CSSList` (most likely a `MediaQuery`)
+     *
+     * @return bool whether the item was removed
+     */
+    public function remove(CSSListItem $itemToRemove): bool
+    {
+        $key = \array_search($itemToRemove, $this->contents, true);
+        if ($key !== false) {
+            unset($this->contents[$key]);
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Replaces an item from the CSS list.
+     *
+     * @param CSSListItem $oldItem
+     *        May be a `RuleSet` (most likely a `DeclarationBlock`), an `Import`, a `Charset`
+     *        or another `CSSList` (most likely a `MediaQuery`)
+     * @param CSSListItem|array<CSSListItem> $newItem
+     */
+    public function replace(CSSListItem $oldItem, $newItem): bool
+    {
+        $key = \array_search($oldItem, $this->contents, true);
+        if ($key !== false) {
+            if (\is_array($newItem)) {
+                \array_splice($this->contents, $key, 1, $newItem);
+            } else {
+                \array_splice($this->contents, $key, 1, [$newItem]);
+            }
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * @param array<int, CSSListItem> $contents
+     */
+    public function setContents(array $contents): void
+    {
+        $this->contents = [];
+        foreach ($contents as $content) {
+            $this->append($content);
+        }
+    }
+
+    /**
+     * Removes a declaration block from the CSS list if it matches all given selectors.
+     *
+     * @param DeclarationBlock|array<Selector>|string $selectors the selectors to match
+     * @param bool $removeAll whether to stop at the first declaration block found or remove all blocks
+     */
+    public function removeDeclarationBlockBySelector($selectors, bool $removeAll = false): void
+    {
+        if ($selectors instanceof DeclarationBlock) {
+            $selectors = $selectors->getSelectors();
+        }
+        if (!\is_array($selectors)) {
+            $selectors = \explode(',', $selectors);
+        }
+        foreach ($selectors as $key => &$selector) {
+            if (!($selector instanceof Selector)) {
+                if (!Selector::isValid($selector)) {
+                    throw new UnexpectedTokenException(
+                        "Selector did not match '" . Selector::SELECTOR_VALIDATION_RX . "'.",
+                        $selector,
+                        'custom'
+                    );
+                }
+                $selector = new Selector($selector);
+            }
+        }
+        foreach ($this->contents as $key => $item) {
+            if (!($item instanceof DeclarationBlock)) {
+                continue;
+            }
+            if ($item->getSelectors() == $selectors) {
+                unset($this->contents[$key]);
+                if (!$removeAll) {
+                    return;
+                }
+            }
+        }
+    }
+
+    protected function renderListContents(OutputFormat $outputFormat): string
+    {
+        $result = '';
+        $isFirst = true;
+        $nextLevelFormat = $outputFormat;
+        if (!$this->isRootList()) {
+            $nextLevelFormat = $outputFormat->nextLevel();
+        }
+        $nextLevelFormatter = $nextLevelFormat->getFormatter();
+        $formatter = $outputFormat->getFormatter();
+        foreach ($this->contents as $listItem) {
+            $renderedCss = $formatter->safely(static function () use ($nextLevelFormat, $listItem): string {
+                return $listItem->render($nextLevelFormat);
+            });
+            if ($renderedCss === null) {
+                continue;
+            }
+            if ($isFirst) {
+                $isFirst = false;
+                $result .= $nextLevelFormatter->spaceBeforeBlocks();
+            } else {
+                $result .= $nextLevelFormatter->spaceBetweenBlocks();
+            }
+            $result .= $renderedCss;
+        }
+
+        if (!$isFirst) {
+            // Had some output
+            $result .= $formatter->spaceAfterBlocks();
+        }
+
+        return $result;
+    }
+
+    /**
+     * Return true if the list can not be further outdented. Only important when rendering.
+     */
+    abstract public function isRootList(): bool;
+
+    /**
+     * Returns the stored items.
+     *
+     * @return array<int<0, max>, CSSListItem>
+     */
+    public function getContents(): array
+    {
+        return $this->contents;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSList/CSSListItem.php b/includes/Dependencies/Sabberworm/CSS/CSSList/CSSListItem.php
new file mode 100644
index 0000000..4d54138
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSList/CSSListItem.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\Commentable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Renderable;
+
+/**
+ * Represents anything that can be in the `$contents` of a `CSSList`.
+ *
+ * The interface does not define any methods to implement.
+ * It's purpose is to allow a single type to be specified for `CSSList::$contents` and manipulation methods thereof.
+ * It extends `Commentable` and `Renderable` because all `CSSListItem`s are both.
+ * This allows implementations to call methods from those interfaces without any additional type checks.
+ */
+interface CSSListItem extends Commentable, Renderable {}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSList/Document.php b/includes/Dependencies/Sabberworm/CSS/CSSList/Document.php
new file mode 100644
index 0000000..9dd9d3b
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSList/Document.php
@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector;
+
+/**
+ * This class represents the root of a parsed CSS file. It contains all top-level CSS contents: mostly declaration
+ * blocks, but also any at-rules encountered (`Import` and `Charset`).
+ */
+class Document extends CSSBlockList
+{
+    /**
+     * @throws SourceException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState): Document
+    {
+        $document = new Document($parserState->currentLine());
+        CSSList::parseList($parserState, $document);
+
+        return $document;
+    }
+
+    /**
+     * Returns all `Selector` objects with the requested specificity found recursively in the tree.
+     *
+     * Note that this does not yield the full `DeclarationBlock` that the selector belongs to
+     * (and, currently, there is no way to get to that).
+     *
+     * @param string|null $specificitySearch
+     *        An optional filter by specificity.
+     *        May contain a comparison operator and a number or just a number (defaults to "==").
+     *
+     * @return list<Selector>
+     *
+     * @example `getSelectorsBySpecificity('>= 100')`
+     */
+    public function getSelectorsBySpecificity(?string $specificitySearch = null): array
+    {
+        return $this->getAllSelectors($specificitySearch);
+    }
+
+    /**
+     * Overrides `render()` to make format argument optional.
+     */
+    public function render(?OutputFormat $outputFormat = null): string
+    {
+        if ($outputFormat === null) {
+            $outputFormat = new OutputFormat();
+        }
+        return $outputFormat->getFormatter()->comments($this) . $this->renderListContents($outputFormat);
+    }
+
+    public function isRootList(): bool
+    {
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/CSSList/KeyFrame.php b/includes/Dependencies/Sabberworm/CSS/CSSList/KeyFrame.php
new file mode 100644
index 0000000..9d1d8df
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/CSSList/KeyFrame.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\AtRule;
+
+class KeyFrame extends CSSList implements AtRule
+{
+    /**
+     * @var non-empty-string
+     */
+    private $vendorKeyFrame = 'keyframes';
+
+    /**
+     * @var non-empty-string
+     */
+    private $animationName = 'none';
+
+    /**
+     * @param non-empty-string $vendorKeyFrame
+     */
+    public function setVendorKeyFrame(string $vendorKeyFrame): void
+    {
+        $this->vendorKeyFrame = $vendorKeyFrame;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function getVendorKeyFrame(): string
+    {
+        return $this->vendorKeyFrame;
+    }
+
+    /**
+     * @param non-empty-string $animationName
+     */
+    public function setAnimationName(string $animationName): void
+    {
+        $this->animationName = $animationName;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function getAnimationName(): string
+    {
+        return $this->animationName;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $formatter = $outputFormat->getFormatter();
+        $result = $formatter->comments($this);
+        $result .= "@{$this->vendorKeyFrame} {$this->animationName}{$formatter->spaceBeforeOpeningBrace()}{";
+        $result .= $this->renderListContents($outputFormat);
+        $result .= '}';
+        return $result;
+    }
+
+    public function isRootList(): bool
+    {
+        return false;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string
+    {
+        return $this->vendorKeyFrame;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleArgs(): string
+    {
+        return $this->animationName;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Comment/Comment.php b/includes/Dependencies/Sabberworm/CSS/Comment/Comment.php
new file mode 100644
index 0000000..ca4b7dd
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Comment/Comment.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Renderable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+
+class Comment implements Positionable, Renderable
+{
+    use Position;
+
+    /**
+     * @var string
+     *
+     * @internal since 8.8.0
+     */
+    protected $commentText;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $commentText = '', ?int $lineNumber = null)
+    {
+        $this->commentText = $commentText;
+        $this->setPosition($lineNumber);
+    }
+
+    public function getComment(): string
+    {
+        return $this->commentText;
+    }
+
+    public function setComment(string $commentText): void
+    {
+        $this->commentText = $commentText;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return '/*' . $this->commentText . '*/';
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Comment/CommentContainer.php b/includes/Dependencies/Sabberworm/CSS/Comment/CommentContainer.php
new file mode 100644
index 0000000..64d5218
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Comment/CommentContainer.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment;
+
+/**
+ * Provides a standard reusable implementation of `Commentable`.
+ *
+ * @internal
+ *
+ * @phpstan-require-implements Commentable
+ */
+trait CommentContainer
+{
+    /**
+     * @var list<Comment>
+     */
+    protected $comments = [];
+
+    /**
+     * @param list<Comment> $comments
+     */
+    public function addComments(array $comments): void
+    {
+        $this->comments = \array_merge($this->comments, $comments);
+    }
+
+    /**
+     * @return list<Comment>
+     */
+    public function getComments(): array
+    {
+        return $this->comments;
+    }
+
+    /**
+     * @param list<Comment> $comments
+     */
+    public function setComments(array $comments): void
+    {
+        $this->comments = $comments;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Comment/Commentable.php b/includes/Dependencies/Sabberworm/CSS/Comment/Commentable.php
new file mode 100644
index 0000000..d6557f3
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Comment/Commentable.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment;
+
+/**
+ * A standard implementation of this interface is available in the `CommentContainer` trait.
+ */
+interface Commentable
+{
+    /**
+     * @param list<Comment> $comments
+     */
+    public function addComments(array $comments): void;
+
+    /**
+     * @return list<Comment>
+     */
+    public function getComments(): array;
+
+    /**
+     * @param list<Comment> $comments
+     */
+    public function setComments(array $comments): void;
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/OutputFormat.php b/includes/Dependencies/Sabberworm/CSS/OutputFormat.php
new file mode 100644
index 0000000..7be3a46
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/OutputFormat.php
@@ -0,0 +1,753 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS;
+
+final class OutputFormat
+{
+    /**
+     * Value format: `"` means double-quote, `'` means single-quote
+     *
+     * @var non-empty-string
+     */
+    private $stringQuotingType = '"';
+
+    /**
+     * Output RGB colors in hash notation if possible
+     *
+     * @var bool
+     */
+    private $usesRgbHashNotation = true;
+
+    /**
+     * Declaration format
+     *
+     * Semicolon after the last rule of a declaration block can be omitted. To do that, set this false.
+     *
+     * @var bool
+     */
+    private $renderSemicolonAfterLastRule = true;
+
+    /**
+     * Spacing
+     * Note that these strings are not sanity-checked: the value should only consist of whitespace
+     * Any newline character will be indented according to the current level.
+     * The triples (After, Before, Between) can be set using a wildcard
+     * (e.g. `$outputFormat->set('Space*Rules', "\n");`)
+     *
+     * @var string
+     */
+    private $spaceAfterRuleName = ' ';
+
+    /**
+     * @var string
+     */
+    private $spaceBeforeRules = '';
+
+    /**
+     * @var string
+     */
+    private $spaceAfterRules = '';
+
+    /**
+     * @var string
+     */
+    private $spaceBetweenRules = '';
+
+    /**
+     * @var string
+     */
+    private $spaceBeforeBlocks = '';
+
+    /**
+     * @var string
+     */
+    private $spaceAfterBlocks = '';
+
+    /**
+     * @var string
+     */
+    private $spaceBetweenBlocks = "\n";
+
+    /**
+     * Content injected in and around at-rule blocks.
+     *
+     * @var string
+     */
+    private $contentBeforeAtRuleBlock = '';
+
+    /**
+     * @var string
+     */
+    private $contentAfterAtRuleBlock = '';
+
+    /**
+     * This is what’s printed before and after the comma if a declaration block contains multiple selectors.
+     *
+     * @var string
+     */
+    private $spaceBeforeSelectorSeparator = '';
+
+    /**
+     * @var string
+     */
+    private $spaceAfterSelectorSeparator = ' ';
+
+    /**
+     * This is what’s inserted before the separator in value lists, by default.
+     *
+     * @var string
+     */
+    private $spaceBeforeListArgumentSeparator = '';
+
+    /**
+     * Keys are separators (e.g. `,`).  Values are the space sequence to insert, or an empty string.
+     *
+     * @var array<non-empty-string, string>
+     */
+    private $spaceBeforeListArgumentSeparators = [];
+
+    /**
+     * This is what’s inserted after the separator in value lists, by default.
+     *
+     * @var string
+     */
+    private $spaceAfterListArgumentSeparator = '';
+
+    /**
+     * Keys are separators (e.g. `,`).  Values are the space sequence to insert, or an empty string.
+     *
+     * @var array<non-empty-string, string>
+     */
+    private $spaceAfterListArgumentSeparators = [];
+
+    /**
+     * @var string
+     */
+    private $spaceBeforeOpeningBrace = ' ';
+
+    /**
+     * Content injected in and around declaration blocks.
+     *
+     * @var string
+     */
+    private $contentBeforeDeclarationBlock = '';
+
+    /**
+     * @var string
+     */
+    private $contentAfterDeclarationBlockSelectors = '';
+
+    /**
+     * @var string
+     */
+    private $contentAfterDeclarationBlock = '';
+
+    /**
+     * Indentation character(s) per level. Only applicable if newlines are used in any of the spacing settings.
+     *
+     * @var string
+     */
+    private $indentation = "\t";
+
+    /**
+     * Output exceptions.
+     *
+     * @var bool
+     */
+    private $shouldIgnoreExceptions = false;
+
+    /**
+     * Render comments for lists and RuleSets
+     *
+     * @var bool
+     */
+    private $shouldRenderComments = false;
+
+    /**
+     * @var OutputFormatter|null
+     */
+    private $outputFormatter;
+
+    /**
+     * @var OutputFormat|null
+     */
+    private $nextLevelFormat;
+
+    /**
+     * @var int<0, max>
+     */
+    private $indentationLevel = 0;
+
+    /**
+     * @return non-empty-string
+     *
+     * @internal
+     */
+    public function getStringQuotingType(): string
+    {
+        return $this->stringQuotingType;
+    }
+
+    /**
+     * @param non-empty-string $quotingType
+     *
+     * @return $this fluent interface
+     */
+    public function setStringQuotingType(string $quotingType): self
+    {
+        $this->stringQuotingType = $quotingType;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function usesRgbHashNotation(): bool
+    {
+        return $this->usesRgbHashNotation;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setRGBHashNotation(bool $usesRgbHashNotation): self
+    {
+        $this->usesRgbHashNotation = $usesRgbHashNotation;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function shouldRenderSemicolonAfterLastRule(): bool
+    {
+        return $this->renderSemicolonAfterLastRule;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSemicolonAfterLastRule(bool $renderSemicolonAfterLastRule): self
+    {
+        $this->renderSemicolonAfterLastRule = $renderSemicolonAfterLastRule;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceAfterRuleName(): string
+    {
+        return $this->spaceAfterRuleName;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceAfterRuleName(string $whitespace): self
+    {
+        $this->spaceAfterRuleName = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBeforeRules(): string
+    {
+        return $this->spaceBeforeRules;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBeforeRules(string $whitespace): self
+    {
+        $this->spaceBeforeRules = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceAfterRules(): string
+    {
+        return $this->spaceAfterRules;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceAfterRules(string $whitespace): self
+    {
+        $this->spaceAfterRules = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBetweenRules(): string
+    {
+        return $this->spaceBetweenRules;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBetweenRules(string $whitespace): self
+    {
+        $this->spaceBetweenRules = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBeforeBlocks(): string
+    {
+        return $this->spaceBeforeBlocks;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBeforeBlocks(string $whitespace): self
+    {
+        $this->spaceBeforeBlocks = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceAfterBlocks(): string
+    {
+        return $this->spaceAfterBlocks;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceAfterBlocks(string $whitespace): self
+    {
+        $this->spaceAfterBlocks = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBetweenBlocks(): string
+    {
+        return $this->spaceBetweenBlocks;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBetweenBlocks(string $whitespace): self
+    {
+        $this->spaceBetweenBlocks = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getContentBeforeAtRuleBlock(): string
+    {
+        return $this->contentBeforeAtRuleBlock;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setBeforeAtRuleBlock(string $content): self
+    {
+        $this->contentBeforeAtRuleBlock = $content;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getContentAfterAtRuleBlock(): string
+    {
+        return $this->contentAfterAtRuleBlock;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setAfterAtRuleBlock(string $content): self
+    {
+        $this->contentAfterAtRuleBlock = $content;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBeforeSelectorSeparator(): string
+    {
+        return $this->spaceBeforeSelectorSeparator;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBeforeSelectorSeparator(string $whitespace): self
+    {
+        $this->spaceBeforeSelectorSeparator = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceAfterSelectorSeparator(): string
+    {
+        return $this->spaceAfterSelectorSeparator;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceAfterSelectorSeparator(string $whitespace): self
+    {
+        $this->spaceAfterSelectorSeparator = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBeforeListArgumentSeparator(): string
+    {
+        return $this->spaceBeforeListArgumentSeparator;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBeforeListArgumentSeparator(string $whitespace): self
+    {
+        $this->spaceBeforeListArgumentSeparator = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @return array<non-empty-string, string>
+     *
+     * @internal
+     */
+    public function getSpaceBeforeListArgumentSeparators(): array
+    {
+        return $this->spaceBeforeListArgumentSeparators;
+    }
+
+    /**
+     * @param array<non-empty-string, string> $separatorSpaces
+     *
+     * @return $this fluent interface
+     */
+    public function setSpaceBeforeListArgumentSeparators(array $separatorSpaces): self
+    {
+        $this->spaceBeforeListArgumentSeparators = $separatorSpaces;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceAfterListArgumentSeparator(): string
+    {
+        return $this->spaceAfterListArgumentSeparator;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceAfterListArgumentSeparator(string $whitespace): self
+    {
+        $this->spaceAfterListArgumentSeparator = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @return array<non-empty-string, string>
+     *
+     * @internal
+     */
+    public function getSpaceAfterListArgumentSeparators(): array
+    {
+        return $this->spaceAfterListArgumentSeparators;
+    }
+
+    /**
+     * @param array<non-empty-string, string> $separatorSpaces
+     *
+     * @return $this fluent interface
+     */
+    public function setSpaceAfterListArgumentSeparators(array $separatorSpaces): self
+    {
+        $this->spaceAfterListArgumentSeparators = $separatorSpaces;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getSpaceBeforeOpeningBrace(): string
+    {
+        return $this->spaceBeforeOpeningBrace;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setSpaceBeforeOpeningBrace(string $whitespace): self
+    {
+        $this->spaceBeforeOpeningBrace = $whitespace;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getContentBeforeDeclarationBlock(): string
+    {
+        return $this->contentBeforeDeclarationBlock;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setBeforeDeclarationBlock(string $content): self
+    {
+        $this->contentBeforeDeclarationBlock = $content;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getContentAfterDeclarationBlockSelectors(): string
+    {
+        return $this->contentAfterDeclarationBlockSelectors;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setAfterDeclarationBlockSelectors(string $content): self
+    {
+        $this->contentAfterDeclarationBlockSelectors = $content;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getContentAfterDeclarationBlock(): string
+    {
+        return $this->contentAfterDeclarationBlock;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setAfterDeclarationBlock(string $content): self
+    {
+        $this->contentAfterDeclarationBlock = $content;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function getIndentation(): string
+    {
+        return $this->indentation;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setIndentation(string $indentation): self
+    {
+        $this->indentation = $indentation;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function shouldIgnoreExceptions(): bool
+    {
+        return $this->shouldIgnoreExceptions;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setIgnoreExceptions(bool $ignoreExceptions): self
+    {
+        $this->shouldIgnoreExceptions = $ignoreExceptions;
+
+        return $this;
+    }
+
+    /**
+     * @internal
+     */
+    public function shouldRenderComments(): bool
+    {
+        return $this->shouldRenderComments;
+    }
+
+    /**
+     * @return $this fluent interface
+     */
+    public function setRenderComments(bool $renderComments): self
+    {
+        $this->shouldRenderComments = $renderComments;
+
+        return $this;
+    }
+
+    /**
+     * @return int<0, max>
+     *
+     * @internal
+     */
+    public function getIndentationLevel(): int
+    {
+        return $this->indentationLevel;
+    }
+
+    /**
+     * @param int<1, max> $numberOfTabs
+     *
+     * @return $this fluent interface
+     */
+    public function indentWithTabs(int $numberOfTabs = 1): self
+    {
+        return $this->setIndentation(\str_repeat("\t", $numberOfTabs));
+    }
+
+    /**
+     * @param int<1, max> $numberOfSpaces
+     *
+     * @return $this fluent interface
+     */
+    public function indentWithSpaces(int $numberOfSpaces = 2): self
+    {
+        return $this->setIndentation(\str_repeat(' ', $numberOfSpaces));
+    }
+
+    /**
+     * @internal since V8.8.0
+     */
+    public function nextLevel(): self
+    {
+        if ($this->nextLevelFormat === null) {
+            $this->nextLevelFormat = clone $this;
+            $this->nextLevelFormat->indentationLevel++;
+            $this->nextLevelFormat->outputFormatter = null;
+        }
+        return $this->nextLevelFormat;
+    }
+
+    public function beLenient(): void
+    {
+        $this->shouldIgnoreExceptions = true;
+    }
+
+    /**
+     * @internal since 8.8.0
+     */
+    public function getFormatter(): OutputFormatter
+    {
+        if ($this->outputFormatter === null) {
+            $this->outputFormatter = new OutputFormatter($this);
+        }
+
+        return $this->outputFormatter;
+    }
+
+    /**
+     * Creates an instance of this class without any particular formatting settings.
+     */
+    public static function create(): self
+    {
+        return new OutputFormat();
+    }
+
+    /**
+     * Creates an instance of this class with a preset for compact formatting.
+     */
+    public static function createCompact(): self
+    {
+        $format = self::create();
+        $format
+            ->setSpaceBeforeRules('')
+            ->setSpaceBetweenRules('')
+            ->setSpaceAfterRules('')
+            ->setSpaceBeforeBlocks('')
+            ->setSpaceBetweenBlocks('')
+            ->setSpaceAfterBlocks('')
+            ->setSpaceAfterRuleName('')
+            ->setSpaceBeforeOpeningBrace('')
+            ->setSpaceAfterSelectorSeparator('')
+            ->setSemicolonAfterLastRule(false)
+            ->setRenderComments(false);
+
+        return $format;
+    }
+
+    /**
+     * Creates an instance of this class with a preset for pretty formatting.
+     */
+    public static function createPretty(): self
+    {
+        $format = self::create();
+        $format
+            ->setSpaceBeforeRules("\n")
+            ->setSpaceBetweenRules("\n")
+            ->setSpaceAfterRules("\n")
+            ->setSpaceBeforeBlocks("\n")
+            ->setSpaceBetweenBlocks("\n\n")
+            ->setSpaceAfterBlocks("\n")
+            ->setSpaceAfterListArgumentSeparators([',' => ' '])
+            ->setRenderComments(true);
+
+        return $format;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/OutputFormatter.php b/includes/Dependencies/Sabberworm/CSS/OutputFormatter.php
new file mode 100644
index 0000000..73a7500
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/OutputFormatter.php
@@ -0,0 +1,235 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\Commentable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\OutputException;
+
+/**
+ * @internal since 8.8.0
+ */
+class OutputFormatter
+{
+    /**
+     * @var OutputFormat
+     */
+    private $outputFormat;
+
+    public function __construct(OutputFormat $outputFormat)
+    {
+        $this->outputFormat = $outputFormat;
+    }
+
+    /**
+     * @param non-empty-string $name
+     *
+     * @throws \InvalidArgumentException
+     */
+    public function space(string $name): string
+    {
+        switch ($name) {
+            case 'AfterRuleName':
+                $spaceString = $this->outputFormat->getSpaceAfterRuleName();
+                break;
+            case 'BeforeRules':
+                $spaceString = $this->outputFormat->getSpaceBeforeRules();
+                break;
+            case 'AfterRules':
+                $spaceString = $this->outputFormat->getSpaceAfterRules();
+                break;
+            case 'BetweenRules':
+                $spaceString = $this->outputFormat->getSpaceBetweenRules();
+                break;
+            case 'BeforeBlocks':
+                $spaceString = $this->outputFormat->getSpaceBeforeBlocks();
+                break;
+            case 'AfterBlocks':
+                $spaceString = $this->outputFormat->getSpaceAfterBlocks();
+                break;
+            case 'BetweenBlocks':
+                $spaceString = $this->outputFormat->getSpaceBetweenBlocks();
+                break;
+            case 'BeforeSelectorSeparator':
+                $spaceString = $this->outputFormat->getSpaceBeforeSelectorSeparator();
+                break;
+            case 'AfterSelectorSeparator':
+                $spaceString = $this->outputFormat->getSpaceAfterSelectorSeparator();
+                break;
+            case 'BeforeOpeningBrace':
+                $spaceString = $this->outputFormat->getSpaceBeforeOpeningBrace();
+                break;
+            case 'BeforeListArgumentSeparator':
+                $spaceString = $this->outputFormat->getSpaceBeforeListArgumentSeparator();
+                break;
+            case 'AfterListArgumentSeparator':
+                $spaceString = $this->outputFormat->getSpaceAfterListArgumentSeparator();
+                break;
+            default:
+                throw new \InvalidArgumentException("Unknown space type: $name", 1740049248);
+        }
+
+        return $this->prepareSpace($spaceString);
+    }
+
+    public function spaceAfterRuleName(): string
+    {
+        return $this->space('AfterRuleName');
+    }
+
+    public function spaceBeforeRules(): string
+    {
+        return $this->space('BeforeRules');
+    }
+
+    public function spaceAfterRules(): string
+    {
+        return $this->space('AfterRules');
+    }
+
+    public function spaceBetweenRules(): string
+    {
+        return $this->space('BetweenRules');
+    }
+
+    public function spaceBeforeBlocks(): string
+    {
+        return $this->space('BeforeBlocks');
+    }
+
+    public function spaceAfterBlocks(): string
+    {
+        return $this->space('AfterBlocks');
+    }
+
+    public function spaceBetweenBlocks(): string
+    {
+        return $this->space('BetweenBlocks');
+    }
+
+    public function spaceBeforeSelectorSeparator(): string
+    {
+        return $this->space('BeforeSelectorSeparator');
+    }
+
+    public function spaceAfterSelectorSeparator(): string
+    {
+        return $this->space('AfterSelectorSeparator');
+    }
+
+    /**
+     * @param non-empty-string $separator
+     */
+    public function spaceBeforeListArgumentSeparator(string $separator): string
+    {
+        $spaceForSeparator = $this->outputFormat->getSpaceBeforeListArgumentSeparators();
+
+        return $spaceForSeparator[$separator] ?? $this->space('BeforeListArgumentSeparator');
+    }
+
+    /**
+     * @param non-empty-string $separator
+     */
+    public function spaceAfterListArgumentSeparator(string $separator): string
+    {
+        $spaceForSeparator = $this->outputFormat->getSpaceAfterListArgumentSeparators();
+
+        return $spaceForSeparator[$separator] ?? $this->space('AfterListArgumentSeparator');
+    }
+
+    public function spaceBeforeOpeningBrace(): string
+    {
+        return $this->space('BeforeOpeningBrace');
+    }
+
+    /**
+     * Runs the given code, either swallowing or passing exceptions, depending on the `ignoreExceptions` setting.
+     */
+    public function safely(callable $callable): ?string
+    {
+        if ($this->outputFormat->shouldIgnoreExceptions()) {
+            // If output exceptions are ignored, run the code with exception guards
+            try {
+                return $callable();
+            } catch (OutputException $e) {
+                return null;
+            } // Do nothing
+        } else {
+            // Run the code as-is
+            return $callable();
+        }
+    }
+
+    /**
+     * Clone of the `implode` function, but calls `render` with the current output format.
+     *
+     * @param array<array-key, Renderable|string> $values
+     */
+    public function implode(string $separator, array $values, bool $increaseLevel = false): string
+    {
+        $result = '';
+        $outputFormat = $this->outputFormat;
+        if ($increaseLevel) {
+            $outputFormat = $outputFormat->nextLevel();
+        }
+        $isFirst = true;
+        foreach ($values as $value) {
+            if ($isFirst) {
+                $isFirst = false;
+            } else {
+                $result .= $separator;
+            }
+            if ($value instanceof Renderable) {
+                $result .= $value->render($outputFormat);
+            } else {
+                $result .= $value;
+            }
+        }
+        return $result;
+    }
+
+    public function removeLastSemicolon(string $string): string
+    {
+        if ($this->outputFormat->shouldRenderSemicolonAfterLastRule()) {
+            return $string;
+        }
+
+        $parts = \explode(';', $string);
+        if (\count($parts) < 2) {
+            return $parts[0];
+        }
+        $lastPart = \array_pop($parts);
+        $nextToLastPart = \array_pop($parts);
+        \array_push($parts, $nextToLastPart . $lastPart);
+
+        return \implode(';', $parts);
+    }
+
+    public function comments(Commentable $commentable): string
+    {
+        if (!$this->outputFormat->shouldRenderComments()) {
+            return '';
+        }
+
+        $result = '';
+        $comments = $commentable->getComments();
+        $lastCommentIndex = \count($comments) - 1;
+
+        foreach ($comments as $i => $comment) {
+            $result .= $comment->render($this->outputFormat);
+            $result .= $i === $lastCommentIndex ? $this->spaceAfterBlocks() : $this->spaceBetweenBlocks();
+        }
+        return $result;
+    }
+
+    private function prepareSpace(string $spaceString): string
+    {
+        return \str_replace("\n", "\n" . $this->indent(), $spaceString);
+    }
+
+    private function indent(): string
+    {
+        return \str_repeat($this->outputFormat->getIndentation(), $this->outputFormat->getIndentationLevel());
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parser.php b/includes/Dependencies/Sabberworm/CSS/Parser.php
new file mode 100644
index 0000000..9cd21b1
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parser.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\Document;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+
+/**
+ * This class parses CSS from text into a data structure.
+ */
+class Parser
+{
+    /**
+     * @var ParserState
+     */
+    private $parserState;
+
+    /**
+     * @param string $text the complete CSS as text (i.e., usually the contents of a CSS file)
+     * @param int<1, max> $lineNumber the line number (starting from 1, not from 0)
+     */
+    public function __construct(string $text, ?Settings $parserSettings = null, int $lineNumber = 1)
+    {
+        if ($parserSettings === null) {
+            $parserSettings = Settings::create();
+        }
+        $this->parserState = new ParserState($text, $parserSettings, $lineNumber);
+    }
+
+    /**
+     * Parses the CSS provided to the constructor and creates a `Document` from it.
+     *
+     * @throws SourceException
+     */
+    public function parse(): Document
+    {
+        return Document::parse($this->parserState);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parsing/Anchor.php b/includes/Dependencies/Sabberworm/CSS/Parsing/Anchor.php
new file mode 100644
index 0000000..edee293
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parsing/Anchor.php
@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing;
+
+/**
+ * @internal since 8.7.0
+ */
+class Anchor
+{
+    /**
+     * @var int<0, max>
+     */
+    private $position;
+
+    /**
+     * @var ParserState
+     */
+    private $parserState;
+
+    /**
+     * @param int<0, max> $position
+     */
+    public function __construct(int $position, ParserState $parserState)
+    {
+        $this->position = $position;
+        $this->parserState = $parserState;
+    }
+
+    public function backtrack(): void
+    {
+        $this->parserState->setPosition($this->position);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parsing/OutputException.php b/includes/Dependencies/Sabberworm/CSS/Parsing/OutputException.php
new file mode 100644
index 0000000..2f151a6
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parsing/OutputException.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing;
+
+/**
+ * Thrown if the CSS parser attempts to print something invalid.
+ */
+final class OutputException extends SourceException {}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parsing/ParserState.php b/includes/Dependencies/Sabberworm/CSS/Parsing/ParserState.php
new file mode 100644
index 0000000..4ef7093
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parsing/ParserState.php
@@ -0,0 +1,464 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\Comment;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Settings;
+
+/**
+ * @internal since 8.7.0
+ */
+class ParserState
+{
+    /**
+     * @var null
+     */
+    public const EOF = null;
+
+    /**
+     * @var Settings
+     */
+    private $parserSettings;
+
+    /**
+     * @var string
+     */
+    private $text;
+
+    /**
+     * @var array<int, string>
+     */
+    private $characters;
+
+    /**
+     * @var int<0, max>
+     */
+    private $currentPosition = 0;
+
+    /**
+     * will only be used if the CSS does not contain an `@charset` declaration
+     *
+     * @var string
+     */
+    private $charset;
+
+    /**
+     * @var int<1, max> $lineNumber
+     */
+    private $lineNumber;
+
+    /**
+     * @param string $text the complete CSS as text (i.e., usually the contents of a CSS file)
+     * @param int<1, max> $lineNumber
+     */
+    public function __construct(string $text, Settings $parserSettings, int $lineNumber = 1)
+    {
+        $this->parserSettings = $parserSettings;
+        $this->text = $text;
+        $this->lineNumber = $lineNumber;
+        $this->setCharset($this->parserSettings->getDefaultCharset());
+    }
+
+    /**
+     * Sets the charset to be used if the CSS does not contain an `@charset` declaration.
+     *
+     * @throws SourceException if the charset is UTF-8 and the content has invalid byte sequences
+     */
+    public function setCharset(string $charset): void
+    {
+        $this->charset = $charset;
+        $this->characters = $this->strsplit($this->text);
+    }
+
+    /**
+     * @return int<1, max>
+     */
+    public function currentLine(): int
+    {
+        return $this->lineNumber;
+    }
+
+    /**
+     * @return int<0, max>
+     */
+    public function currentColumn(): int
+    {
+        return $this->currentPosition;
+    }
+
+    public function getSettings(): Settings
+    {
+        return $this->parserSettings;
+    }
+
+    public function anchor(): Anchor
+    {
+        return new Anchor($this->currentPosition, $this);
+    }
+
+    /**
+     * @param int<0, max> $position
+     */
+    public function setPosition(int $position): void
+    {
+        $this->currentPosition = $position;
+    }
+
+    /**
+     * @return non-empty-string
+     *
+     * @throws UnexpectedTokenException
+     */
+    public function parseIdentifier(bool $ignoreCase = true): string
+    {
+        if ($this->isEnd()) {
+            throw new UnexpectedEOFException('', '', 'identifier', $this->lineNumber);
+        }
+        $result = $this->parseCharacter(true);
+        if ($result === null) {
+            throw new UnexpectedTokenException('', $this->peek(5), 'identifier', $this->lineNumber);
+        }
+        $character = null;
+        while (!$this->isEnd() && ($character = $this->parseCharacter(true)) !== null) {
+            if (\preg_match('/[a-zA-Z0-9\\x{00A0}-\\x{FFFF}_-]/Sux', $character)) {
+                $result .= $character;
+            } else {
+                $result .= '\\' . $character;
+            }
+        }
+        if ($ignoreCase) {
+            $result = $this->strtolower($result);
+        }
+
+        return $result;
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    public function parseCharacter(bool $isForIdentifier): ?string
+    {
+        if ($this->peek() === '\\') {
+            $this->consume('\\');
+            if ($this->comes('\\n') || $this->comes('\\r')) {
+                return '';
+            }
+            if (\preg_match('/[0-9a-fA-F]/Su', $this->peek()) === 0) {
+                return $this->consume(1);
+            }
+            $hexCodePoint = $this->consumeExpression('/^[0-9a-fA-F]{1,6}/u', 6);
+            if ($this->strlen($hexCodePoint) < 6) {
+                // Consume whitespace after incomplete unicode escape
+                if (\preg_match('/\\s/isSu', $this->peek())) {
+                    if ($this->comes('\\r\\n')) {
+                        $this->consume(2);
+                    } else {
+                        $this->consume(1);
+                    }
+                }
+            }
+            $codePoint = \intval($hexCodePoint, 16);
+            $utf32EncodedCharacter = '';
+            for ($i = 0; $i < 4; ++$i) {
+                $utf32EncodedCharacter .= \chr($codePoint & 0xff);
+                $codePoint = $codePoint >> 8;
+            }
+            return \iconv('utf-32le', $this->charset, $utf32EncodedCharacter);
+        }
+        if ($isForIdentifier) {
+            $peek = \ord($this->peek());
+            // Ranges: a-z A-Z 0-9 - _
+            if (
+                ($peek >= 97 && $peek <= 122)
+                || ($peek >= 65 && $peek <= 90)
+                || ($peek >= 48 && $peek <= 57)
+                || ($peek === 45)
+                || ($peek === 95)
+                || ($peek > 0xa1)
+            ) {
+                return $this->consume(1);
+            }
+        } else {
+            return $this->consume(1);
+        }
+
+        return null;
+    }
+
+    /**
+     * @return list<Comment>
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    public function consumeWhiteSpace(): array
+    {
+        $comments = [];
+        do {
+            while (\preg_match('/\\s/isSu', $this->peek()) === 1) {
+                $this->consume(1);
+            }
+            if ($this->parserSettings->usesLenientParsing()) {
+                try {
+                    $comment = $this->consumeComment();
+                } catch (UnexpectedEOFException $e) {
+                    $this->currentPosition = \count($this->characters);
+                    break;
+                }
+            } else {
+                $comment = $this->consumeComment();
+            }
+            if ($comment instanceof Comment) {
+                $comments[] = $comment;
+            }
+        } while ($comment instanceof Comment);
+
+        return $comments;
+    }
+
+    /**
+     * @param non-empty-string $string
+     */
+    public function comes(string $string, bool $caseInsensitive = false): bool
+    {
+        $peek = $this->peek(\strlen($string));
+
+        return ($peek !== '') && $this->streql($peek, $string, $caseInsensitive);
+    }
+
+    /**
+     * @param int<1, max> $length
+     * @param int<0, max> $offset
+     */
+    public function peek(int $length = 1, int $offset = 0): string
+    {
+        $offset += $this->currentPosition;
+        if ($offset >= \count($this->characters)) {
+            return '';
+        }
+
+        return $this->substr($offset, $length);
+    }
+
+    /**
+     * @param string|int<1, max> $value
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    public function consume($value = 1): string
+    {
+        if (\is_string($value)) {
+            $numberOfLines = \substr_count($value, "\n");
+            $length = $this->strlen($value);
+            if (!$this->streql($this->substr($this->currentPosition, $length), $value)) {
+                throw new UnexpectedTokenException(
+                    $value,
+                    $this->peek(\max($length, 5)),
+                    'literal',
+                    $this->lineNumber
+                );
+            }
+
+            $this->lineNumber += $numberOfLines;
+            $this->currentPosition += $this->strlen($value);
+            $result = $value;
+        } else {
+            if ($this->currentPosition + $value > \count($this->characters)) {
+                throw new UnexpectedEOFException((string) $value, $this->peek(5), 'count', $this->lineNumber);
+            }
+
+            $result = $this->substr($this->currentPosition, $value);
+            $numberOfLines = \substr_count($result, "\n");
+            $this->lineNumber += $numberOfLines;
+            $this->currentPosition += $value;
+        }
+
+        return $result;
+    }
+
+    /**
+     * @param string $expression
+     * @param int<1, max>|null $maximumLength
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    public function consumeExpression(string $expression, ?int $maximumLength = null): string
+    {
+        $matches = null;
+        $input = ($maximumLength !== null) ? $this->peek($maximumLength) : $this->inputLeft();
+        if (\preg_match($expression, $input, $matches, PREG_OFFSET_CAPTURE) !== 1) {
+            throw new UnexpectedTokenException($expression, $this->peek(5), 'expression', $this->lineNumber);
+        }
+
+        return $this->consume($matches[0][0]);
+    }
+
+    /**
+     * @return Comment|false
+     */
+    public function consumeComment()
+    {
+        $lineNumber = $this->lineNumber;
+        $comment = null;
+
+        if ($this->comes('/*')) {
+            $this->consume(1);
+            $comment = '';
+            while (($char = $this->consume(1)) !== '') {
+                $comment .= $char;
+                if ($this->comes('*/')) {
+                    $this->consume(2);
+                    break;
+                }
+            }
+        }
+
+        // We skip the * which was included in the comment.
+        return \is_string($comment) ? new Comment(\substr($comment, 1), $lineNumber) : false;
+    }
+
+    public function isEnd(): bool
+    {
+        return $this->currentPosition >= \count($this->characters);
+    }
+
+    /**
+     * @param list<string|self::EOF>|string|self::EOF $stopCharacters
+     * @param array<int, Comment> $comments
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    public function consumeUntil(
+        $stopCharacters,
+        bool $includeEnd = false,
+        bool $consumeEnd = false,
+        array &$comments = []
+    ): string {
+        $stopCharacters = \is_array($stopCharacters) ? $stopCharacters : [$stopCharacters];
+        $consumedCharacters = '';
+        $start = $this->currentPosition;
+
+        while (!$this->isEnd()) {
+            $character = $this->consume(1);
+            if (\in_array($character, $stopCharacters, true)) {
+                if ($includeEnd) {
+                    $consumedCharacters .= $character;
+                } elseif (!$consumeEnd) {
+                    $this->currentPosition -= $this->strlen($character);
+                }
+                return $consumedCharacters;
+            }
+            $consumedCharacters .= $character;
+            $comment = $this->consumeComment();
+            if ($comment instanceof Comment) {
+                $comments[] = $comment;
+            }
+        }
+
+        if (\in_array(self::EOF, $stopCharacters, true)) {
+            return $consumedCharacters;
+        }
+
+        $this->currentPosition = $start;
+        throw new UnexpectedEOFException(
+            'One of ("' . \implode('","', $stopCharacters) . '")',
+            $this->peek(5),
+            'search',
+            $this->lineNumber
+        );
+    }
+
+    private function inputLeft(): string
+    {
+        return $this->substr($this->currentPosition, -1);
+    }
+
+    public function streql(string $string1, string $string2, bool $caseInsensitive = true): bool
+    {
+        return $caseInsensitive
+            ? ($this->strtolower($string1) === $this->strtolower($string2))
+            : ($string1 === $string2);
+    }
+
+    /**
+     * @param int<1, max> $numberOfCharacters
+     */
+    public function backtrack(int $numberOfCharacters): void
+    {
+        $this->currentPosition -= $numberOfCharacters;
+    }
+
+    /**
+     * @return int<0, max>
+     */
+    public function strlen(string $string): int
+    {
+        return $this->parserSettings->hasMultibyteSupport()
+            ? \mb_strlen($string, $this->charset)
+            : \strlen($string);
+    }
+
+    /**
+     * @param int<0, max> $offset
+     */
+    private function substr(int $offset, int $length): string
+    {
+        if ($length < 0) {
+            $length = \count($this->characters) - $offset + $length;
+        }
+        if ($offset + $length > \count($this->characters)) {
+            $length = \count($this->characters) - $offset;
+        }
+        $result = '';
+        while ($length > 0) {
+            $result .= $this->characters[$offset];
+            $offset++;
+            $length--;
+        }
+
+        return $result;
+    }
+
+    /**
+     * @return ($string is non-empty-string ? non-empty-string : string)
+     */
+    private function strtolower(string $string): string
+    {
+        return $this->parserSettings->hasMultibyteSupport()
+            ? \mb_strtolower($string, $this->charset)
+            : \strtolower($string);
+    }
+
+    /**
+     * @return list<string>
+     *
+     * @throws SourceException if the charset is UTF-8 and the string contains invalid byte sequences
+     */
+    private function strsplit(string $string): array
+    {
+        if ($this->parserSettings->hasMultibyteSupport()) {
+            if ($this->streql($this->charset, 'utf-8')) {
+                $result = \preg_split('//u', $string, -1, PREG_SPLIT_NO_EMPTY);
+                if (!\is_array($result)) {
+                    throw new SourceException('`preg_split` failed with error ' . \preg_last_error());
+                }
+            } else {
+                $length = \mb_strlen($string, $this->charset);
+                $result = [];
+                for ($i = 0; $i < $length; ++$i) {
+                    $result[] = \mb_substr($string, $i, 1, $this->charset);
+                }
+            }
+        } else {
+            $result = ($string !== '') ? \str_split($string) : [];
+        }
+
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parsing/SourceException.php b/includes/Dependencies/Sabberworm/CSS/Parsing/SourceException.php
new file mode 100644
index 0000000..0b73d5e
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parsing/SourceException.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+
+class SourceException extends \Exception implements Positionable
+{
+    use Position;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $message, ?int $lineNumber = null)
+    {
+        $this->setPosition($lineNumber);
+        if ($lineNumber !== null) {
+            $message .= " [line no: $lineNumber]";
+        }
+        parent::__construct($message);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedEOFException.php b/includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedEOFException.php
new file mode 100644
index 0000000..291d242
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedEOFException.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing;
+
+/**
+ * Thrown if the CSS parser encounters end of file it did not expect.
+ *
+ * Extends `UnexpectedTokenException` in order to preserve backwards compatibility.
+ */
+final class UnexpectedEOFException extends UnexpectedTokenException {}
diff --git a/includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedTokenException.php b/includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedTokenException.php
new file mode 100644
index 0000000..53605a1
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Parsing/UnexpectedTokenException.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing;
+
+/**
+ * Thrown if the CSS parser encounters a token it did not expect.
+ */
+class UnexpectedTokenException extends SourceException
+{
+    /**
+     * @param 'literal'|'identifier'|'count'|'expression'|'search'|'custom' $matchType
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $expected, string $found, string $matchType = 'literal', ?int $lineNumber = null)
+    {
+        $message = "Token “{$expected}” ({$matchType}) not found. Got “{$found}”.";
+        if ($matchType === 'search') {
+            $message = "Search for “{$expected}” returned no results. Context: “{$found}”.";
+        } elseif ($matchType === 'count') {
+            $message = "Next token was expected to have {$expected} chars. Context: “{$found}”.";
+        } elseif ($matchType === 'identifier') {
+            $message = "Identifier expected. Got “{$found}”";
+        } elseif ($matchType === 'custom') {
+            $message = \trim("$expected $found");
+        }
+
+        parent::__construct($message, $lineNumber);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Position/Position.php b/includes/Dependencies/Sabberworm/CSS/Position/Position.php
new file mode 100644
index 0000000..00ecffa
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Position/Position.php
@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position;
+
+/**
+ * Provides a standard reusable implementation of `Positionable`.
+ *
+ * @internal
+ *
+ * @phpstan-require-implements Positionable
+ */
+trait Position
+{
+    /**
+     * @var int<1, max>|null
+     */
+    protected $lineNumber;
+
+    /**
+     * @var int<0, max>|null
+     */
+    protected $columnNumber;
+
+    /**
+     * @return int<1, max>|null
+     */
+    public function getLineNumber(): ?int
+    {
+        return $this->lineNumber;
+    }
+
+    /**
+     * @return int<0, max>|null
+     */
+    public function getColumnNumber(): ?int
+    {
+        return $this->columnNumber;
+    }
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     * @param int<0, max>|null $columnNumber
+     *
+     * @return $this fluent interface
+     */
+    public function setPosition(?int $lineNumber, ?int $columnNumber = null): Positionable
+    {
+        $this->lineNumber = $lineNumber;
+        $this->columnNumber = $columnNumber;
+
+        return $this;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Position/Positionable.php b/includes/Dependencies/Sabberworm/CSS/Position/Positionable.php
new file mode 100644
index 0000000..b5cc357
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Position/Positionable.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position;
+
+/**
+ * Represents a CSS item that may have a position in the source CSS document (line number and possibly column number).
+ *
+ * A standard implementation of this interface is available in the `Position` trait.
+ */
+interface Positionable
+{
+    /**
+     * @return int<1, max>|null
+     */
+    public function getLineNumber(): ?int;
+
+    /**
+     * @return int<0, max>|null
+     */
+    public function getColumnNumber(): ?int;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     * @param int<0, max>|null $columnNumber
+     *
+     * @return $this fluent interface
+     */
+    public function setPosition(?int $lineNumber, ?int $columnNumber = null): Positionable;
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/AtRule.php b/includes/Dependencies/Sabberworm/CSS/Property/AtRule.php
new file mode 100644
index 0000000..db89939
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/AtRule.php
@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\CSSListItem;
+
+/**
+ * Note that `CSSListItem` extends both `Commentable` and `Renderable`,
+ * so concrete classes implementing this interface must also implement those.
+ */
+interface AtRule extends CSSListItem
+{
+    /**
+     * Since there are more set rules than block rules,
+     * we’re whitelisting the block rules and have anything else be treated as a set rule.
+     *
+     * @var non-empty-string
+     *
+     * @internal since 8.5.2
+     */
+    public const BLOCK_RULES = 'media/document/supports/region-style/font-feature-values';
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string;
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/CSSNamespace.php b/includes/Dependencies/Sabberworm/CSS/Property/CSSNamespace.php
new file mode 100644
index 0000000..70da9e6
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/CSSNamespace.php
@@ -0,0 +1,97 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\CSSString;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\URL;
+
+/**
+ * `CSSNamespace` represents an `@namespace` rule.
+ */
+class CSSNamespace implements AtRule, Positionable
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * @var CSSString|URL
+     */
+    private $url;
+
+    /**
+     * @var string|null
+     */
+    private $prefix;
+
+    /**
+     * @param CSSString|URL $url
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct($url, ?string $prefix = null, ?int $lineNumber = null)
+    {
+        $this->url = $url;
+        $this->prefix = $prefix;
+        $this->setPosition($lineNumber);
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return '@namespace ' . ($this->prefix === null ? '' : $this->prefix . ' ')
+            . $this->url->render($outputFormat) . ';';
+    }
+
+    /**
+     * @return CSSString|URL
+     */
+    public function getUrl()
+    {
+        return $this->url;
+    }
+
+    public function getPrefix(): ?string
+    {
+        return $this->prefix;
+    }
+
+    /**
+     * @param CSSString|URL $url
+     */
+    public function setUrl($url): void
+    {
+        $this->url = $url;
+    }
+
+    public function setPrefix(string $prefix): void
+    {
+        $this->prefix = $prefix;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string
+    {
+        return 'namespace';
+    }
+
+    /**
+     * @return array{0: CSSString|URL|non-empty-string, 1?: CSSString|URL}
+     */
+    public function atRuleArgs(): array
+    {
+        $result = [$this->url];
+        if (\is_string($this->prefix) && $this->prefix !== '') {
+            \array_unshift($result, $this->prefix);
+        }
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/Charset.php b/includes/Dependencies/Sabberworm/CSS/Property/Charset.php
new file mode 100644
index 0000000..fa814d8
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/Charset.php
@@ -0,0 +1,74 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\CSSString;
+
+/**
+ * Class representing an `@charset` rule.
+ *
+ * The following restrictions apply:
+ * - May not be found in any CSSList other than the Document.
+ * - May only appear at the very top of a Document’s contents.
+ * - Must not appear more than once.
+ */
+class Charset implements AtRule, Positionable
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * @var CSSString
+     */
+    private $charset;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(CSSString $charset, ?int $lineNumber = null)
+    {
+        $this->charset = $charset;
+        $this->setPosition($lineNumber);
+    }
+
+    /**
+     * @param string|CSSString $charset
+     */
+    public function setCharset($charset): void
+    {
+        $charset = $charset instanceof CSSString ? $charset : new CSSString($charset);
+        $this->charset = $charset;
+    }
+
+    public function getCharset(): string
+    {
+        return $this->charset->getString();
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return "{$outputFormat->getFormatter()->comments($this)}@charset {$this->charset->render($outputFormat)};";
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string
+    {
+        return 'charset';
+    }
+
+    public function atRuleArgs(): CSSString
+    {
+        return $this->charset;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/Import.php b/includes/Dependencies/Sabberworm/CSS/Property/Import.php
new file mode 100644
index 0000000..99d4957
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/Import.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\URL;
+
+/**
+ * Class representing an `@import` rule.
+ */
+class Import implements AtRule, Positionable
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * @var URL
+     */
+    private $location;
+
+    /**
+     * @var string|null
+     */
+    private $mediaQuery;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(URL $location, ?string $mediaQuery, ?int $lineNumber = null)
+    {
+        $this->location = $location;
+        $this->mediaQuery = $mediaQuery;
+        $this->setPosition($lineNumber);
+    }
+
+    public function setLocation(URL $location): void
+    {
+        $this->location = $location;
+    }
+
+    public function getLocation(): URL
+    {
+        return $this->location;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return $outputFormat->getFormatter()->comments($this) . '@import ' . $this->location->render($outputFormat)
+            . ($this->mediaQuery === null ? '' : ' ' . $this->mediaQuery) . ';';
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string
+    {
+        return 'import';
+    }
+
+    /**
+     * @return array{0: URL, 1?: non-empty-string}
+     */
+    public function atRuleArgs(): array
+    {
+        $result = [$this->location];
+        if (\is_string($this->mediaQuery) && $this->mediaQuery !== '') {
+            $result[] = $this->mediaQuery;
+        }
+
+        return $result;
+    }
+
+    public function getMediaQuery(): ?string
+    {
+        return $this->mediaQuery;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/KeyframeSelector.php b/includes/Dependencies/Sabberworm/CSS/Property/KeyframeSelector.php
new file mode 100644
index 0000000..2bd780a
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/KeyframeSelector.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property;
+
+class KeyframeSelector extends Selector
+{
+    /**
+     * regexp for specificity calculations
+     *
+     * @var string
+     *
+     * @internal since 8.5.2
+     */
+    public const SELECTOR_VALIDATION_RX = '/
+    ^(
+        (?:
+            [a-zA-Z0-9\\x{00A0}-\\x{FFFF}_^$|*="\'~\\[\\]()\\-\\s\\.:#+>]* # any sequence of valid unescaped characters
+            (?:\\\\.)?                                                     # a single escaped character
+            (?:([\'"]).*?(?<!\\\\)\\2)?                                    # a quoted text like [id="example"]
+        )*
+    )|
+    (\\d+%)                                                                # keyframe animation progress percentage (e.g. 50%)
+    $
+    /ux';
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/Selector.php b/includes/Dependencies/Sabberworm/CSS/Property/Selector.php
new file mode 100644
index 0000000..74a5dd7
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/Selector.php
@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector\SpecificityCalculator;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Renderable;
+
+/**
+ * Class representing a single CSS selector. Selectors have to be split by the comma prior to being passed into this
+ * class.
+ */
+class Selector implements Renderable
+{
+    /**
+     * regexp for specificity calculations
+     *
+     * @var string
+     *
+     * @internal since 8.5.2
+     */
+    public const SELECTOR_VALIDATION_RX = '/
+        ^(
+            (?:
+                [a-zA-Z0-9\\x{00A0}-\\x{FFFF}_^$|*="\'~\\[\\]()\\-\\s\\.:#+>,]* # any sequence of valid unescaped characters
+                (?:\\\\.)?                                                      # a single escaped character
+                (?:([\'"]).*?(?<!\\\\)\\2)?                                     # a quoted text like [id="example"]
+            )*
+        )$
+        /ux';
+
+    /**
+     * @var string
+     */
+    private $selector;
+
+    /**
+     * @internal since V8.8.0
+     */
+    public static function isValid(string $selector): bool
+    {
+        // Note: We need to use `static::` here as the constant is overridden in the `KeyframeSelector` class.
+        $numberOfMatches = \preg_match(static::SELECTOR_VALIDATION_RX, $selector);
+
+        return $numberOfMatches === 1;
+    }
+
+    public function __construct(string $selector)
+    {
+        $this->setSelector($selector);
+    }
+
+    public function getSelector(): string
+    {
+        return $this->selector;
+    }
+
+    public function setSelector(string $selector): void
+    {
+        $this->selector = \trim($selector);
+    }
+
+    /**
+     * @return int<0, max>
+     */
+    public function getSpecificity(): int
+    {
+        return SpecificityCalculator::calculate($this->selector);
+    }
+
+    public function render(OutputFormat $outputFormat): string
+    {
+        return $this->getSelector();
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Property/Selector/SpecificityCalculator.php b/includes/Dependencies/Sabberworm/CSS/Property/Selector/SpecificityCalculator.php
new file mode 100644
index 0000000..661d433
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Property/Selector/SpecificityCalculator.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector;
+
+/**
+ * Utility class to calculate the specificity of a CSS selector.
+ *
+ * The results are cached to avoid recalculating the specificity of the same selector multiple times.
+ */
+final class SpecificityCalculator
+{
+    /**
+     * regexp for specificity calculations
+     *
+     * @var non-empty-string
+     */
+    private const NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX = '/
+        (\\.[\\w]+)                   # classes
+        |
+        \\[(\\w+)                     # attributes
+        |
+        (\\:(                         # pseudo classes
+            link|visited|active
+            |hover|focus
+            |lang
+            |target
+            |enabled|disabled|checked|indeterminate
+            |root
+            |nth-child|nth-last-child|nth-of-type|nth-last-of-type
+            |first-child|last-child|first-of-type|last-of-type
+            |only-child|only-of-type
+            |empty|contains
+        ))
+        /ix';
+
+    /**
+     * regexp for specificity calculations
+     *
+     * @var non-empty-string
+     */
+    private const ELEMENTS_AND_PSEUDO_ELEMENTS_RX = '/
+        ((^|[\\s\\+\\>\\~]+)[\\w]+   # elements
+        |
+        \\:{1,2}(                    # pseudo-elements
+            after|before|first-letter|first-line|selection
+        ))
+        /ix';
+
+    /**
+     * @var array<string, int<0, max>>
+     */
+    private static $cache = [];
+
+    /**
+     * Calculates the specificity of the given CSS selector.
+     *
+     * @return int<0, max>
+     *
+     * @internal
+     */
+    public static function calculate(string $selector): int
+    {
+        if (!isset(self::$cache[$selector])) {
+            $a = 0;
+            /// @todo should exclude \# as well as "#"
+            $matches = null;
+            $b = \substr_count($selector, '#');
+            $c = \preg_match_all(self::NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX, $selector, $matches);
+            $d = \preg_match_all(self::ELEMENTS_AND_PSEUDO_ELEMENTS_RX, $selector, $matches);
+            self::$cache[$selector] = ($a * 1000) + ($b * 100) + ($c * 10) + $d;
+        }
+
+        return self::$cache[$selector];
+    }
+
+    /**
+     * Clears the cache in order to lower memory usage.
+     */
+    public static function clearCache(): void
+    {
+        self::$cache = [];
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Renderable.php b/includes/Dependencies/Sabberworm/CSS/Renderable.php
new file mode 100644
index 0000000..ce13789
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Renderable.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS;
+
+interface Renderable
+{
+    public function render(OutputFormat $outputFormat): string;
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Rule/Rule.php b/includes/Dependencies/Sabberworm/CSS/Rule/Rule.php
new file mode 100644
index 0000000..24309ba
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Rule/Rule.php
@@ -0,0 +1,198 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Rule;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\Comment;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\Commentable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSElement;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\RuleValueList;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value\Value;
+
+/**
+ * `Rule`s just have a string key (the rule) and a 'Value'.
+ *
+ * In CSS, `Rule`s are expressed as follows: “key: value[0][0] value[0][1], value[1][0] value[1][1];”
+ */
+class Rule implements Commentable, CSSElement, Positionable
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * @var non-empty-string
+     */
+    private $rule;
+
+    /**
+     * @var RuleValueList|string|null
+     */
+    private $value;
+
+    /**
+     * @var bool
+     */
+    private $isImportant = false;
+
+    /**
+     * @param non-empty-string $rule
+     * @param int<1, max>|null $lineNumber
+     * @param int<0, max>|null $columnNumber
+     */
+    public function __construct(string $rule, ?int $lineNumber = null, ?int $columnNumber = null)
+    {
+        $this->rule = $rule;
+        $this->setPosition($lineNumber, $columnNumber);
+    }
+
+    /**
+     * @param list<Comment> $commentsBeforeRule
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState, array $commentsBeforeRule = []): Rule
+    {
+        $comments = \array_merge($commentsBeforeRule, $parserState->consumeWhiteSpace());
+        $rule = new Rule(
+            $parserState->parseIdentifier(!$parserState->comes('--')),
+            $parserState->currentLine(),
+            $parserState->currentColumn()
+        );
+        $rule->setComments($comments);
+        $rule->addComments($parserState->consumeWhiteSpace());
+        $parserState->consume(':');
+        $value = Value::parseValue($parserState, self::listDelimiterForRule($rule->getRule()));
+        $rule->setValue($value);
+        $parserState->consumeWhiteSpace();
+        if ($parserState->comes('!')) {
+            $parserState->consume('!');
+            $parserState->consumeWhiteSpace();
+            $parserState->consume('important');
+            $rule->setIsImportant(true);
+        }
+        $parserState->consumeWhiteSpace();
+        while ($parserState->comes(';')) {
+            $parserState->consume(';');
+        }
+
+        return $rule;
+    }
+
+    /**
+     * Returns a list of delimiters (or separators).
+     * The first item is the innermost separator (or, put another way, the highest-precedence operator).
+     * The sequence continues to the outermost separator (or lowest-precedence operator).
+     *
+     * @param non-empty-string $rule
+     *
+     * @return list<non-empty-string>
+     */
+    private static function listDelimiterForRule(string $rule): array
+    {
+        if (\preg_match('/^font($|-)/', $rule)) {
+            return [',', '/', ' '];
+        }
+
+        switch ($rule) {
+            case 'src':
+                return [' ', ','];
+            default:
+                return [',', ' ', '/'];
+        }
+    }
+
+    /**
+     * @param non-empty-string $rule
+     */
+    public function setRule(string $rule): void
+    {
+        $this->rule = $rule;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function getRule(): string
+    {
+        return $this->rule;
+    }
+
+    /**
+     * @return RuleValueList|string|null
+     */
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    /**
+     * @param RuleValueList|string|null $value
+     */
+    public function setValue($value): void
+    {
+        $this->value = $value;
+    }
+
+    /**
+     * Adds a value to the existing value. Value will be appended if a `RuleValueList` exists of the given type.
+     * Otherwise, the existing value will be wrapped by one.
+     *
+     * @param RuleValueList|array<int, RuleValueList> $value
+     */
+    public function addValue($value, string $type = ' '): void
+    {
+        if (!\is_array($value)) {
+            $value = [$value];
+        }
+        if (!($this->value instanceof RuleValueList) || $this->value->getListSeparator() !== $type) {
+            $currentValue = $this->value;
+            $this->value = new RuleValueList($type, $this->getLineNumber());
+            if ($currentValue !== null && $currentValue !== '') {
+                $this->value->addListComponent($currentValue);
+            }
+        }
+        foreach ($value as $valueItem) {
+            $this->value->addListComponent($valueItem);
+        }
+    }
+
+    public function setIsImportant(bool $isImportant): void
+    {
+        $this->isImportant = $isImportant;
+    }
+
+    public function getIsImportant(): bool
+    {
+        return $this->isImportant;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $formatter = $outputFormat->getFormatter();
+        $result = "{$formatter->comments($this)}{$this->rule}:{$formatter->spaceAfterRuleName()}";
+        if ($this->value instanceof Value) { // Can also be a ValueList
+            $result .= $this->value->render($outputFormat);
+        } else {
+            $result .= $this->value;
+        }
+        if ($this->isImportant) {
+            $result .= ' !important';
+        }
+        $result .= ';';
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/RuleSet/AtRuleSet.php b/includes/Dependencies/Sabberworm/CSS/RuleSet/AtRuleSet.php
new file mode 100644
index 0000000..c55e759
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/RuleSet/AtRuleSet.php
@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\AtRule;
+
+/**
+ * This class represents rule sets for generic at-rules which are not covered by specific classes, i.e., not
+ * `@import`, `@charset` or `@media`.
+ *
+ * A common example for this is `@font-face`.
+ */
+class AtRuleSet extends RuleSet implements AtRule
+{
+    /**
+     * @var non-empty-string
+     */
+    private $type;
+
+    /**
+     * @var string
+     */
+    private $arguments;
+
+    /**
+     * @param non-empty-string $type
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $type, string $arguments = '', ?int $lineNumber = null)
+    {
+        parent::__construct($lineNumber);
+        $this->type = $type;
+        $this->arguments = $arguments;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function atRuleName(): string
+    {
+        return $this->type;
+    }
+
+    public function atRuleArgs(): string
+    {
+        return $this->arguments;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $formatter = $outputFormat->getFormatter();
+        $result = $formatter->comments($this);
+        $arguments = $this->arguments;
+        if ($arguments !== '') {
+            $arguments = ' ' . $arguments;
+        }
+        $result .= "@{$this->type}$arguments{$formatter->spaceBeforeOpeningBrace()}{";
+        $result .= $this->renderRules($outputFormat);
+        $result .= '}';
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/RuleSet/DeclarationBlock.php b/includes/Dependencies/Sabberworm/CSS/RuleSet/DeclarationBlock.php
new file mode 100644
index 0000000..4ef22d4
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/RuleSet/DeclarationBlock.php
@@ -0,0 +1,301 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSElement;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\CSSList;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\CSSListItem;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\KeyFrame;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\OutputException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\KeyframeSelector;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Property\Selector;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Rule\Rule;
+
+/**
+ * This class represents a `RuleSet` constrained by a `Selector`.
+ *
+ * It contains an array of selector objects (comma-separated in the CSS) as well as the rules to be applied to the
+ * matching elements.
+ *
+ * Declaration blocks usually appear directly inside a `Document` or another `CSSList` (mostly a `MediaQuery`).
+ *
+ * Note that `CSSListItem` extends both `Commentable` and `Renderable`, so those interfaces must also be implemented.
+ */
+class DeclarationBlock implements CSSElement, CSSListItem, Positionable, RuleContainer
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * @var array<Selector|string>
+     */
+    private $selectors = [];
+
+    /**
+     * @var RuleSet
+     */
+    private $ruleSet;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(?int $lineNumber = null)
+    {
+        $this->ruleSet = new RuleSet($lineNumber);
+        $this->setPosition($lineNumber);
+    }
+
+    /**
+     * @throws UnexpectedTokenException
+     * @throws UnexpectedEOFException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState, ?CSSList $list = null): ?DeclarationBlock
+    {
+        $comments = [];
+        $result = new DeclarationBlock($parserState->currentLine());
+        try {
+            $selectors = [];
+            $selectorParts = [];
+            $stringWrapperCharacter = null;
+            $functionNestingLevel = 0;
+            $consumedNextCharacter = false;
+            static $stopCharacters = ['{', '}', '\'', '"', '(', ')', ','];
+            do {
+                if (!$consumedNextCharacter) {
+                    $selectorParts[] = $parserState->consume(1);
+                }
+                $selectorParts[] = $parserState->consumeUntil($stopCharacters, false, false, $comments);
+                $nextCharacter = $parserState->peek();
+                $consumedNextCharacter = false;
+                switch ($nextCharacter) {
+                    case '\'':
+                        // The fallthrough is intentional.
+                    case '"':
+                        if (!\is_string($stringWrapperCharacter)) {
+                            $stringWrapperCharacter = $nextCharacter;
+                        } elseif ($stringWrapperCharacter === $nextCharacter) {
+                            if (\substr(\end($selectorParts), -1) !== '\\') {
+                                $stringWrapperCharacter = null;
+                            }
+                        }
+                        break;
+                    case '(':
+                        if (!\is_string($stringWrapperCharacter)) {
+                            ++$functionNestingLevel;
+                        }
+                        break;
+                    case ')':
+                        if (!\is_string($stringWrapperCharacter)) {
+                            if ($functionNestingLevel <= 0) {
+                                throw new UnexpectedTokenException('anything but', ')');
+                            }
+                            --$functionNestingLevel;
+                        }
+                        break;
+                    case ',':
+                        if (!\is_string($stringWrapperCharacter) && $functionNestingLevel === 0) {
+                            $selectors[] = \implode('', $selectorParts);
+                            $selectorParts = [];
+                            $parserState->consume(1);
+                            $consumedNextCharacter = true;
+                        }
+                        break;
+                }
+            } while (!\in_array($nextCharacter, ['{', '}'], true) || \is_string($stringWrapperCharacter));
+            if ($functionNestingLevel !== 0) {
+                throw new UnexpectedTokenException(')', $nextCharacter);
+            }
+            $selectors[] = \implode('', $selectorParts); // add final or only selector
+            $result->setSelectors($selectors, $list);
+            if ($parserState->comes('{')) {
+                $parserState->consume(1);
+            }
+        } catch (UnexpectedTokenException $e) {
+            if ($parserState->getSettings()->usesLenientParsing()) {
+                if (!$parserState->comes('}')) {
+                    $parserState->consumeUntil('}', false, true);
+                }
+                return null;
+            } else {
+                throw $e;
+            }
+        }
+        $result->setComments($comments);
+
+        RuleSet::parseRuleSet($parserState, $result->getRuleSet());
+
+        return $result;
+    }
+
+    /**
+     * @param array<Selector|string>|string $selectors
+     *
+     * @throws UnexpectedTokenException
+     */
+    public function setSelectors($selectors, ?CSSList $list = null): void
+    {
+        if (\is_array($selectors)) {
+            $this->selectors = $selectors;
+        } else {
+            $this->selectors = \explode(',', $selectors);
+        }
+        foreach ($this->selectors as $key => $selector) {
+            if (!($selector instanceof Selector)) {
+                if ($list === null || !($list instanceof KeyFrame)) {
+                    if (!Selector::isValid($selector)) {
+                        throw new UnexpectedTokenException(
+                            "Selector did not match '" . Selector::SELECTOR_VALIDATION_RX . "'.",
+                            $selector,
+                            'custom'
+                        );
+                    }
+                    $this->selectors[$key] = new Selector($selector);
+                } else {
+                    if (!KeyframeSelector::isValid($selector)) {
+                        throw new UnexpectedTokenException(
+                            "Selector did not match '" . KeyframeSelector::SELECTOR_VALIDATION_RX . "'.",
+                            $selector,
+                            'custom'
+                        );
+                    }
+                    $this->selectors[$key] = new KeyframeSelector($selector);
+                }
+            }
+        }
+    }
+
+    /**
+     * Remove one of the selectors of the block.
+     *
+     * @param Selector|string $selectorToRemove
+     */
+    public function removeSelector($selectorToRemove): bool
+    {
+        if ($selectorToRemove instanceof Selector) {
+            $selectorToRemove = $selectorToRemove->getSelector();
+        }
+        foreach ($this->selectors as $key => $selector) {
+            if ($selector->getSelector() === $selectorToRemove) {
+                unset($this->selectors[$key]);
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * @return array<Selector>
+     */
+    public function getSelectors(): array
+    {
+        return $this->selectors;
+    }
+
+    public function getRuleSet(): RuleSet
+    {
+        return $this->ruleSet;
+    }
+
+    /**
+     * @see RuleSet::addRule()
+     */
+    public function addRule(Rule $ruleToAdd, ?Rule $sibling = null): void
+    {
+        $this->ruleSet->addRule($ruleToAdd, $sibling);
+    }
+
+    /**
+     * @see RuleSet::getRules()
+     *
+     * @return array<int<0, max>, Rule>
+     */
+    public function getRules(?string $searchPattern = null): array
+    {
+        return $this->ruleSet->getRules($searchPattern);
+    }
+
+    /**
+     * @see RuleSet::setRules()
+     *
+     * @param array<Rule> $rules
+     */
+    public function setRules(array $rules): void
+    {
+        $this->ruleSet->setRules($rules);
+    }
+
+    /**
+     * @see RuleSet::getRulesAssoc()
+     *
+     * @return array<string, Rule>
+     */
+    public function getRulesAssoc(?string $searchPattern = null): array
+    {
+        return $this->ruleSet->getRulesAssoc($searchPattern);
+    }
+
+    /**
+     * @see RuleSet::removeRule()
+     */
+    public function removeRule(Rule $ruleToRemove): void
+    {
+        $this->ruleSet->removeRule($ruleToRemove);
+    }
+
+    /**
+     * @see RuleSet::removeMatchingRules()
+     */
+    public function removeMatchingRules(string $searchPattern): void
+    {
+        $this->ruleSet->removeMatchingRules($searchPattern);
+    }
+
+    /**
+     * @see RuleSet::removeAllRules()
+     */
+    public function removeAllRules(): void
+    {
+        $this->ruleSet->removeAllRules();
+    }
+
+    /**
+     * @return non-empty-string
+     *
+     * @throws OutputException
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $formatter = $outputFormat->getFormatter();
+        $result = $formatter->comments($this);
+        if (\count($this->selectors) === 0) {
+            // If all the selectors have been removed, this declaration block becomes invalid
+            throw new OutputException(
+                'Attempt to print declaration block with missing selector',
+                $this->getLineNumber()
+            );
+        }
+        $result .= $outputFormat->getContentBeforeDeclarationBlock();
+        $result .= $formatter->implode(
+            $formatter->spaceBeforeSelectorSeparator() . ',' . $formatter->spaceAfterSelectorSeparator(),
+            $this->selectors
+        );
+        $result .= $outputFormat->getContentAfterDeclarationBlockSelectors();
+        $result .= $formatter->spaceBeforeOpeningBrace() . '{';
+        $result .= $this->ruleSet->render($outputFormat);
+        $result .= '}';
+        $result .= $outputFormat->getContentAfterDeclarationBlock();
+
+        return $result;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/RuleSet/RuleContainer.php b/includes/Dependencies/Sabberworm/CSS/RuleSet/RuleContainer.php
new file mode 100644
index 0000000..65d6abf
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/RuleSet/RuleContainer.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Rule\Rule;
+
+/**
+ * Represents a CSS item that contains `Rules`, defining the methods to manipulate them.
+ */
+interface RuleContainer
+{
+    public function addRule(Rule $ruleToAdd, ?Rule $sibling = null): void;
+
+    public function removeRule(Rule $ruleToRemove): void;
+
+    public function removeMatchingRules(string $searchPattern): void;
+
+    public function removeAllRules(): void;
+
+    /**
+     * @param array<Rule> $rules
+     */
+    public function setRules(array $rules): void;
+
+    /**
+     * @return array<int<0, max>, Rule>
+     */
+    public function getRules(?string $searchPattern = null): array;
+
+    /**
+     * @return array<string, Rule>
+     */
+    public function getRulesAssoc(?string $searchPattern = null): array;
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/RuleSet/RuleSet.php b/includes/Dependencies/Sabberworm/CSS/RuleSet/RuleSet.php
new file mode 100644
index 0000000..6b5bf1d
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/RuleSet/RuleSet.php
@@ -0,0 +1,375 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\RuleSet;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Comment\CommentContainer;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSElement;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSList\CSSListItem;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Rule\Rule;
+
+/**
+ * This class is a container for individual 'Rule's.
+ *
+ * The most common form of a rule set is one constrained by a selector, i.e., a `DeclarationBlock`.
+ * However, unknown `AtRule`s (like `@font-face`) are rule sets as well.
+ *
+ * If you want to manipulate a `RuleSet`, use the methods `addRule(Rule $rule)`, `getRules()` and `removeRule($rule)`
+ * (which accepts either a `Rule` or a rule name; optionally suffixed by a dash to remove all related rules).
+ *
+ * Note that `CSSListItem` extends both `Commentable` and `Renderable`, so those interfaces must also be implemented.
+ */
+class RuleSet implements CSSElement, CSSListItem, Positionable, RuleContainer
+{
+    use CommentContainer;
+    use Position;
+
+    /**
+     * the rules in this rule set, using the property name as the key,
+     * with potentially multiple rules per property name.
+     *
+     * @var array<string, array<int<0, max>, Rule>>
+     */
+    private $rules = [];
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(?int $lineNumber = null)
+    {
+        $this->setPosition($lineNumber);
+    }
+
+    /**
+     * @throws UnexpectedTokenException
+     * @throws UnexpectedEOFException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parseRuleSet(ParserState $parserState, RuleSet $ruleSet): void
+    {
+        while ($parserState->comes(';')) {
+            $parserState->consume(';');
+        }
+        while (true) {
+            $commentsBeforeRule = $parserState->consumeWhiteSpace();
+            if ($parserState->comes('}')) {
+                break;
+            }
+            $rule = null;
+            if ($parserState->getSettings()->usesLenientParsing()) {
+                try {
+                    $rule = Rule::parse($parserState, $commentsBeforeRule);
+                } catch (UnexpectedTokenException $e) {
+                    try {
+                        $consumedText = $parserState->consumeUntil(["\n", ';', '}'], true);
+                        // We need to “unfind” the matches to the end of the ruleSet as this will be matched later
+                        if ($parserState->streql(\substr($consumedText, -1), '}')) {
+                            $parserState->backtrack(1);
+                        } else {
+                            while ($parserState->comes(';')) {
+                                $parserState->consume(';');
+                            }
+                        }
+                    } catch (UnexpectedTokenException $e) {
+                        // We’ve reached the end of the document. Just close the RuleSet.
+                        return;
+                    }
+                }
+            } else {
+                $rule = Rule::parse($parserState, $commentsBeforeRule);
+            }
+            if ($rule instanceof Rule) {
+                $ruleSet->addRule($rule);
+            }
+        }
+        $parserState->consume('}');
+    }
+
+    /**
+     * @throws \UnexpectedValueException
+     *         if the last `Rule` is needed as a basis for setting position, but does not have a valid position,
+     *         which should never happen
+     */
+    public function addRule(Rule $ruleToAdd, ?Rule $sibling = null): void
+    {
+        $propertyName = $ruleToAdd->getRule();
+        if (!isset($this->rules[$propertyName])) {
+            $this->rules[$propertyName] = [];
+        }
+
+        $position = \count($this->rules[$propertyName]);
+
+        if ($sibling !== null) {
+            $siblingIsInSet = false;
+            $siblingPosition = \array_search($sibling, $this->rules[$propertyName], true);
+            if ($siblingPosition !== false) {
+                $siblingIsInSet = true;
+                $position = $siblingPosition;
+            } else {
+                $siblingIsInSet = $this->hasRule($sibling);
+                if ($siblingIsInSet) {
+                    // Maintain ordering within `$this->rules[$propertyName]`
+                    // by inserting before first `Rule` with a same-or-later position than the sibling.
+                    foreach ($this->rules[$propertyName] as $index => $rule) {
+                        if (self::comparePositionable($rule, $sibling) >= 0) {
+                            $position = $index;
+                            break;
+                        }
+                    }
+                }
+            }
+            if ($siblingIsInSet) {
+                // Increment column number of all existing rules on same line, starting at sibling
+                $siblingLineNumber = $sibling->getLineNumber();
+                $siblingColumnNumber = $sibling->getColumnNumber();
+                foreach ($this->rules as $rulesForAProperty) {
+                    foreach ($rulesForAProperty as $rule) {
+                        if (
+                            $rule->getLineNumber() === $siblingLineNumber &&
+                            $rule->getColumnNumber() >= $siblingColumnNumber
+                        ) {
+                            $rule->setPosition($siblingLineNumber, $rule->getColumnNumber() + 1);
+                        }
+                    }
+                }
+                $ruleToAdd->setPosition($siblingLineNumber, $siblingColumnNumber);
+            }
+        }
+
+        if ($ruleToAdd->getLineNumber() === null) {
+            //this node is added manually, give it the next best line
+            $columnNumber = $ruleToAdd->getColumnNumber() ?? 0;
+            $rules = $this->getRules();
+            $rulesCount = \count($rules);
+            if ($rulesCount > 0) {
+                $last = $rules[$rulesCount - 1];
+                $lastsLineNumber = $last->getLineNumber();
+                if (!\is_int($lastsLineNumber)) {
+                    throw new \UnexpectedValueException(
+                        'A Rule without a line number was found during addRule',
+                        1750718399
+                    );
+                }
+                $ruleToAdd->setPosition($lastsLineNumber + 1, $columnNumber);
+            } else {
+                $ruleToAdd->setPosition(1, $columnNumber);
+            }
+        } elseif ($ruleToAdd->getColumnNumber() === null) {
+            $ruleToAdd->setPosition($ruleToAdd->getLineNumber(), 0);
+        }
+
+        \array_splice($this->rules[$propertyName], $position, 0, [$ruleToAdd]);
+    }
+
+    /**
+     * Returns all rules matching the given rule name
+     *
+     * @example $ruleSet->getRules('font') // returns array(0 => $rule, …) or array().
+     *
+     * @example $ruleSet->getRules('font-')
+     *          //returns an array of all rules either beginning with font- or matching font.
+     *
+     * @param string|null $searchPattern
+     *        Pattern to search for. If null, returns all rules.
+     *        If the pattern ends with a dash, all rules starting with the pattern are returned
+     *        as well as one matching the pattern with the dash excluded.
+     *
+     * @return array<int<0, max>, Rule>
+     */
+    public function getRules(?string $searchPattern = null): array
+    {
+        $result = [];
+        foreach ($this->rules as $propertyName => $rules) {
+            // Either no search rule is given or the search rule matches the found rule exactly
+            // or the search rule ends in “-” and the found rule starts with the search rule.
+            if (
+                $searchPattern === null || $propertyName === $searchPattern
+                || (
+                    \strrpos($searchPattern, '-') === \strlen($searchPattern) - \strlen('-')
+                    && (\strpos($propertyName, $searchPattern) === 0
+                        || $propertyName === \substr($searchPattern, 0, -1))
+                )
+            ) {
+                $result = \array_merge($result, $rules);
+            }
+        }
+        \usort($result, [self::class, 'comparePositionable']);
+
+        return $result;
+    }
+
+    /**
+     * Overrides all the rules of this set.
+     *
+     * @param array<Rule> $rules The rules to override with.
+     */
+    public function setRules(array $rules): void
+    {
+        $this->rules = [];
+        foreach ($rules as $rule) {
+            $this->addRule($rule);
+        }
+    }
+
+    /**
+     * Returns all rules matching the given pattern and returns them in an associative array with the rule’s name
+     * as keys. This method exists mainly for backwards-compatibility and is really only partially useful.
+     *
+     * Note: This method loses some information: Calling this (with an argument of `background-`) on a declaration block
+     * like `{ background-color: green; background-color; rgba(0, 127, 0, 0.7); }` will only yield an associative array
+     * containing the rgba-valued rule while `getRules()` would yield an indexed array containing both.
+     *
+     * @param string|null $searchPattern
+     *        Pattern to search for. If null, returns all rules. If the pattern ends with a dash,
+     *        all rules starting with the pattern are returned as well as one matching the pattern with the dash
+     *        excluded.
+     *
+     * @return array<string, Rule>
+     */
+    public function getRulesAssoc(?string $searchPattern = null): array
+    {
+        /** @var array<string, Rule> $result */
+        $result = [];
+        foreach ($this->getRules($searchPattern) as $rule) {
+            $result[$rule->getRule()] = $rule;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Removes a `Rule` from this `RuleSet` by identity.
+     */
+    public function removeRule(Rule $ruleToRemove): void
+    {
+        $nameOfPropertyToRemove = $ruleToRemove->getRule();
+        if (!isset($this->rules[$nameOfPropertyToRemove])) {
+            return;
+        }
+        foreach ($this->rules[$nameOfPropertyToRemove] as $key => $rule) {
+            if ($rule === $ruleToRemove) {
+                unset($this->rules[$nameOfPropertyToRemove][$key]);
+            }
+        }
+    }
+
+    /**
+     * Removes rules by property name or search pattern.
+     *
+     * @param string $searchPattern
+     *        pattern to remove.
+     *        If the pattern ends in a dash,
+     *        all rules starting with the pattern are removed as well as one matching the pattern with the dash
+     *        excluded.
+     */
+    public function removeMatchingRules(string $searchPattern): void
+    {
+        foreach ($this->rules as $propertyName => $rules) {
+            // Either the search rule matches the found rule exactly
+            // or the search rule ends in “-” and the found rule starts with the search rule or equals it
+            // (without the trailing dash).
+            if (
+                $propertyName === $searchPattern
+                || (\strrpos($searchPattern, '-') === \strlen($searchPattern) - \strlen('-')
+                    && (\strpos($propertyName, $searchPattern) === 0
+                        || $propertyName === \substr($searchPattern, 0, -1)))
+            ) {
+                unset($this->rules[$propertyName]);
+            }
+        }
+    }
+
+    public function removeAllRules(): void
+    {
+        $this->rules = [];
+    }
+
+    /**
+     * @internal
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return $this->renderRules($outputFormat);
+    }
+
+    protected function renderRules(OutputFormat $outputFormat): string
+    {
+        $result = '';
+        $isFirst = true;
+        $nextLevelFormat = $outputFormat->nextLevel();
+        foreach ($this->getRules() as $rule) {
+            $nextLevelFormatter = $nextLevelFormat->getFormatter();
+            $renderedRule = $nextLevelFormatter->safely(static function () use ($rule, $nextLevelFormat): string {
+                return $rule->render($nextLevelFormat);
+            });
+            if ($renderedRule === null) {
+                continue;
+            }
+            if ($isFirst) {
+                $isFirst = false;
+                $result .= $nextLevelFormatter->spaceBeforeRules();
+            } else {
+                $result .= $nextLevelFormatter->spaceBetweenRules();
+            }
+            $result .= $renderedRule;
+        }
+
+        $formatter = $outputFormat->getFormatter();
+        if (!$isFirst) {
+            // Had some output
+            $result .= $formatter->spaceAfterRules();
+        }
+
+        return $formatter->removeLastSemicolon($result);
+    }
+
+    /**
+     * @return int negative if `$first` is before `$second`; zero if they have the same position; positive otherwise
+     *
+     * @throws \UnexpectedValueException if either argument does not have a valid position, which should never happen
+     */
+    private static function comparePositionable(Positionable $first, Positionable $second): int
+    {
+        $firstsLineNumber = $first->getLineNumber();
+        $secondsLineNumber = $second->getLineNumber();
+        if (!\is_int($firstsLineNumber) || !\is_int($secondsLineNumber)) {
+            throw new \UnexpectedValueException(
+                'A Rule without a line number was passed to comparePositionable',
+                1750637683
+            );
+        }
+
+        if ($firstsLineNumber === $secondsLineNumber) {
+            $firstsColumnNumber = $first->getColumnNumber();
+            $secondsColumnNumber = $second->getColumnNumber();
+            if (!\is_int($firstsColumnNumber) || !\is_int($secondsColumnNumber)) {
+                throw new \UnexpectedValueException(
+                    'A Rule without a column number was passed to comparePositionable',
+                    1750637761
+                );
+            }
+            return $firstsColumnNumber - $secondsColumnNumber;
+        }
+
+        return $firstsLineNumber - $secondsLineNumber;
+    }
+
+    private function hasRule(Rule $rule): bool
+    {
+        foreach ($this->rules as $rulesForAProperty) {
+            if (\in_array($rule, $rulesForAProperty, true)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Settings.php b/includes/Dependencies/Sabberworm/CSS/Settings.php
new file mode 100644
index 0000000..fe39117
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Settings.php
@@ -0,0 +1,124 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS;
+
+/**
+ * Parser settings class.
+ *
+ * Configure parser behaviour here.
+ */
+class Settings
+{
+    /**
+     * Multi-byte string support.
+     *
+     * If `true` (`mbstring` extension must be enabled), will use (slower) `mb_strlen`, `mb_convert_case`, `mb_substr`
+     * and `mb_strpos` functions. Otherwise, the normal (ASCII-Only) functions will be used.
+     *
+     * @var bool
+     */
+    private $multibyteSupport;
+
+    /**
+     * The default charset for the CSS if no `@charset` declaration is found. Defaults to utf-8.
+     *
+     * @var non-empty-string
+     */
+    private $defaultCharset = 'utf-8';
+
+    /**
+     * Whether the parser silently ignore invalid rules instead of choking on them.
+     *
+     * @var bool
+     */
+    private $lenientParsing = true;
+
+    private function __construct()
+    {
+        $this->multibyteSupport = \extension_loaded('mbstring');
+    }
+
+    public static function create(): self
+    {
+        return new Settings();
+    }
+
+    /**
+     * Enables/disables multi-byte string support.
+     *
+     * If `true` (`mbstring` extension must be enabled), will use (slower) `mb_strlen`, `mb_convert_case`, `mb_substr`
+     * and `mb_strpos` functions. Otherwise, the normal (ASCII-Only) functions will be used.
+     *
+     * @return $this fluent interface
+     */
+    public function withMultibyteSupport(bool $multibyteSupport = true): self
+    {
+        $this->multibyteSupport = $multibyteSupport;
+
+        return $this;
+    }
+
+    /**
+     * Sets the charset to be used if the CSS does not contain an `@charset` declaration.
+     *
+     * @param non-empty-string $defaultCharset
+     *
+     * @return $this fluent interface
+     */
+    public function withDefaultCharset(string $defaultCharset): self
+    {
+        $this->defaultCharset = $defaultCharset;
+
+        return $this;
+    }
+
+    /**
+     * Configures whether the parser should silently ignore invalid rules.
+     *
+     * @return $this fluent interface
+     */
+    public function withLenientParsing(bool $usesLenientParsing = true): self
+    {
+        $this->lenientParsing = $usesLenientParsing;
+
+        return $this;
+    }
+
+    /**
+     * Configures the parser to choke on invalid rules.
+     *
+     * @return $this fluent interface
+     */
+    public function beStrict(): self
+    {
+        return $this->withLenientParsing(false);
+    }
+
+    /**
+     * @internal
+     */
+    public function hasMultibyteSupport(): bool
+    {
+        return $this->multibyteSupport;
+    }
+
+    /**
+     * @return non-empty-string
+     *
+     * @internal
+     */
+    public function getDefaultCharset(): string
+    {
+        return $this->defaultCharset;
+    }
+
+    /**
+     * @internal
+     */
+    public function usesLenientParsing(): bool
+    {
+        return $this->lenientParsing;
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/CSSFunction.php b/includes/Dependencies/Sabberworm/CSS/Value/CSSFunction.php
new file mode 100644
index 0000000..b185a01
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/CSSFunction.php
@@ -0,0 +1,116 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+/**
+ * A `CSSFunction` represents a special kind of value that also contains a function name and where the values are the
+ * function’s arguments. It also handles equals-sign-separated argument lists like `filter: alpha(opacity=90);`.
+ */
+class CSSFunction extends ValueList
+{
+    /**
+     * @var non-empty-string
+     *
+     * @internal since 8.8.0
+     */
+    protected $name;
+
+    /**
+     * @param non-empty-string $name
+     * @param RuleValueList|array<Value|string> $arguments
+     * @param non-empty-string $separator
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $name, $arguments, string $separator = ',', ?int $lineNumber = null)
+    {
+        if ($arguments instanceof RuleValueList) {
+            $separator = $arguments->getListSeparator();
+            $arguments = $arguments->getListComponents();
+        }
+        $this->name = $name;
+        $this->setPosition($lineNumber); // TODO: redundant?
+        parent::__construct($arguments, $separator, $lineNumber);
+    }
+
+    /**
+     * @throws SourceException
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState, bool $ignoreCase = false): CSSFunction
+    {
+        $name = self::parseName($parserState, $ignoreCase);
+        $parserState->consume('(');
+        $arguments = self::parseArguments($parserState);
+
+        $result = new CSSFunction($name, $arguments, ',', $parserState->currentLine());
+        $parserState->consume(')');
+
+        return $result;
+    }
+
+    /**
+     * @throws SourceException
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseName(ParserState $parserState, bool $ignoreCase = false): string
+    {
+        return $parserState->parseIdentifier($ignoreCase);
+    }
+
+    /**
+     * @return Value|string
+     *
+     * @throws SourceException
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseArguments(ParserState $parserState)
+    {
+        return Value::parseValue($parserState, ['=', ' ', ',']);
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    /**
+     * @param non-empty-string $name
+     */
+    public function setName(string $name): void
+    {
+        $this->name = $name;
+    }
+
+    /**
+     * @return array<Value|string>
+     */
+    public function getArguments(): array
+    {
+        return $this->components;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $arguments = parent::render($outputFormat);
+        return "{$this->name}({$arguments})";
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/CSSString.php b/includes/Dependencies/Sabberworm/CSS/Value/CSSString.php
new file mode 100644
index 0000000..4d2d648
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/CSSString.php
@@ -0,0 +1,95 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+/**
+ * This class is a wrapper for quoted strings to distinguish them from keywords.
+ *
+ * `CSSString`s always output with double quotes.
+ */
+class CSSString extends PrimitiveValue
+{
+    /**
+     * @var string
+     */
+    private $string;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $string, ?int $lineNumber = null)
+    {
+        $this->string = $string;
+        parent::__construct($lineNumber);
+    }
+
+    /**
+     * @throws SourceException
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState): CSSString
+    {
+        $begin = $parserState->peek();
+        $quote = null;
+        if ($begin === "'") {
+            $quote = "'";
+        } elseif ($begin === '"') {
+            $quote = '"';
+        }
+        if ($quote !== null) {
+            $parserState->consume($quote);
+        }
+        $result = '';
+        $content = null;
+        if ($quote === null) {
+            // Unquoted strings end in whitespace or with braces, brackets, parentheses
+            while (\preg_match('/[\\s{}()<>\\[\\]]/isu', $parserState->peek()) !== 1) {
+                $result .= $parserState->parseCharacter(false);
+            }
+        } else {
+            while (!$parserState->comes($quote)) {
+                $content = $parserState->parseCharacter(false);
+                if ($content === null) {
+                    throw new SourceException(
+                        "Non-well-formed quoted string {$parserState->peek(3)}",
+                        $parserState->currentLine()
+                    );
+                }
+                $result .= $content;
+            }
+            $parserState->consume($quote);
+        }
+        return new CSSString($result, $parserState->currentLine());
+    }
+
+    public function setString(string $string): void
+    {
+        $this->string = $string;
+    }
+
+    public function getString(): string
+    {
+        return $this->string;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $string = \addslashes($this->string);
+        $string = \str_replace("\n", '\\A', $string);
+        return $outputFormat->getStringQuotingType() . $string . $outputFormat->getStringQuotingType();
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/CalcFunction.php b/includes/Dependencies/Sabberworm/CSS/Value/CalcFunction.php
new file mode 100644
index 0000000..871ba45
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/CalcFunction.php
@@ -0,0 +1,105 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+class CalcFunction extends CSSFunction
+{
+    /**
+     * @var int
+     */
+    private const T_OPERAND = 1;
+
+    /**
+     * @var int
+     */
+    private const T_OPERATOR = 2;
+
+    /**
+     * @throws UnexpectedTokenException
+     * @throws UnexpectedEOFException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState, bool $ignoreCase = false): CSSFunction
+    {
+        $operators = ['+', '-', '*', '/'];
+        $function = $parserState->parseIdentifier();
+        if ($parserState->peek() !== '(') {
+            // Found ; or end of line before an opening bracket
+            throw new UnexpectedTokenException('(', $parserState->peek(), 'literal', $parserState->currentLine());
+        } elseif ($function !== 'calc') {
+            // Found invalid calc definition. Example calc (...
+            throw new UnexpectedTokenException('calc', $function, 'literal', $parserState->currentLine());
+        }
+        $parserState->consume('(');
+        $calcRuleValueList = new CalcRuleValueList($parserState->currentLine());
+        $list = new RuleValueList(',', $parserState->currentLine());
+        $nestingLevel = 0;
+        $lastComponentType = null;
+        while (!$parserState->comes(')') || $nestingLevel > 0) {
+            if ($parserState->isEnd() && $nestingLevel === 0) {
+                break;
+            }
+
+            $parserState->consumeWhiteSpace();
+            if ($parserState->comes('(')) {
+                $nestingLevel++;
+                $calcRuleValueList->addListComponent($parserState->consume(1));
+                $parserState->consumeWhiteSpace();
+                continue;
+            } elseif ($parserState->comes(')')) {
+                $nestingLevel--;
+                $calcRuleValueList->addListComponent($parserState->consume(1));
+                $parserState->consumeWhiteSpace();
+                continue;
+            }
+            if ($lastComponentType !== CalcFunction::T_OPERAND) {
+                $value = Value::parsePrimitiveValue($parserState);
+                $calcRuleValueList->addListComponent($value);
+                $lastComponentType = CalcFunction::T_OPERAND;
+            } else {
+                if (\in_array($parserState->peek(), $operators, true)) {
+                    if (($parserState->comes('-') || $parserState->comes('+'))) {
+                        if (
+                            $parserState->peek(1, -1) !== ' '
+                            || !($parserState->comes('- ')
+                                || $parserState->comes('+ '))
+                        ) {
+                            throw new UnexpectedTokenException(
+                                " {$parserState->peek()} ",
+                                $parserState->peek(1, -1) . $parserState->peek(2),
+                                'literal',
+                                $parserState->currentLine()
+                            );
+                        }
+                    }
+                    $calcRuleValueList->addListComponent($parserState->consume(1));
+                    $lastComponentType = CalcFunction::T_OPERATOR;
+                } else {
+                    throw new UnexpectedTokenException(
+                        \sprintf(
+                            'Next token was expected to be an operand of type %s. Instead "%s" was found.',
+                            \implode(', ', $operators),
+                            $parserState->peek()
+                        ),
+                        '',
+                        'custom',
+                        $parserState->currentLine()
+                    );
+                }
+            }
+            $parserState->consumeWhiteSpace();
+        }
+        $list->addListComponent($calcRuleValueList);
+        if (!$parserState->isEnd()) {
+            $parserState->consume(')');
+        }
+        return new CalcFunction($function, $list, ',', $parserState->currentLine());
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/CalcRuleValueList.php b/includes/Dependencies/Sabberworm/CSS/Value/CalcRuleValueList.php
new file mode 100644
index 0000000..db789f0
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/CalcRuleValueList.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+
+class CalcRuleValueList extends RuleValueList
+{
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(?int $lineNumber = null)
+    {
+        parent::__construct(',', $lineNumber);
+    }
+
+    public function render(OutputFormat $outputFormat): string
+    {
+        return $outputFormat->getFormatter()->implode(' ', $this->components);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/Color.php b/includes/Dependencies/Sabberworm/CSS/Value/Color.php
new file mode 100644
index 0000000..0cfa3c6
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/Color.php
@@ -0,0 +1,390 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+/**
+ * `Color's can be input in the form #rrggbb, #rgb or schema(val1, val2, …) but are always stored as an array of
+ * ('s' => val1, 'c' => val2, 'h' => val3, …) and output in the second form.
+ */
+class Color extends CSSFunction
+{
+    /**
+     * @param array<non-empty-string, Value|string> $colorValues
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(array $colorValues, ?int $lineNumber = null)
+    {
+        parent::__construct(\implode('', \array_keys($colorValues)), $colorValues, ',', $lineNumber);
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState, bool $ignoreCase = false): CSSFunction
+    {
+        return $parserState->comes('#')
+            ? self::parseHexColor($parserState)
+            : self::parseColorFunction($parserState);
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseHexColor(ParserState $parserState): Color
+    {
+        $parserState->consume('#');
+        $hexValue = $parserState->parseIdentifier(false);
+        if ($parserState->strlen($hexValue) === 3) {
+            $hexValue = $hexValue[0] . $hexValue[0] . $hexValue[1] . $hexValue[1] . $hexValue[2] . $hexValue[2];
+        } elseif ($parserState->strlen($hexValue) === 4) {
+            $hexValue = $hexValue[0] . $hexValue[0] . $hexValue[1] . $hexValue[1] . $hexValue[2] . $hexValue[2]
+                . $hexValue[3] . $hexValue[3];
+        }
+
+        if ($parserState->strlen($hexValue) === 8) {
+            $colorValues = [
+                'r' => new Size(\intval($hexValue[0] . $hexValue[1], 16), null, true, $parserState->currentLine()),
+                'g' => new Size(\intval($hexValue[2] . $hexValue[3], 16), null, true, $parserState->currentLine()),
+                'b' => new Size(\intval($hexValue[4] . $hexValue[5], 16), null, true, $parserState->currentLine()),
+                'a' => new Size(
+                    \round(self::mapRange(\intval($hexValue[6] . $hexValue[7], 16), 0, 255, 0, 1), 2),
+                    null,
+                    true,
+                    $parserState->currentLine()
+                ),
+            ];
+        } elseif ($parserState->strlen($hexValue) === 6) {
+            $colorValues = [
+                'r' => new Size(\intval($hexValue[0] . $hexValue[1], 16), null, true, $parserState->currentLine()),
+                'g' => new Size(\intval($hexValue[2] . $hexValue[3], 16), null, true, $parserState->currentLine()),
+                'b' => new Size(\intval($hexValue[4] . $hexValue[5], 16), null, true, $parserState->currentLine()),
+            ];
+        } else {
+            throw new UnexpectedTokenException(
+                'Invalid hex color value',
+                $hexValue,
+                'custom',
+                $parserState->currentLine()
+            );
+        }
+
+        return new Color($colorValues, $parserState->currentLine());
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseColorFunction(ParserState $parserState): CSSFunction
+    {
+        $colorValues = [];
+
+        $colorMode = $parserState->parseIdentifier(true);
+        $parserState->consumeWhiteSpace();
+        $parserState->consume('(');
+
+        // CSS Color Module Level 4 says that `rgb` and `rgba` are now aliases; likewise `hsl` and `hsla`.
+        // So, attempt to parse with the `a`, and allow for it not being there.
+        switch ($colorMode) {
+            case 'rgb':
+                $colorModeForParsing = 'rgba';
+                $mayHaveOptionalAlpha = true;
+                break;
+            case 'hsl':
+                $colorModeForParsing = 'hsla';
+                $mayHaveOptionalAlpha = true;
+                break;
+            case 'rgba':
+                // This is handled identically to the following case.
+            case 'hsla':
+                $colorModeForParsing = $colorMode;
+                $mayHaveOptionalAlpha = true;
+                break;
+            default:
+                $colorModeForParsing = $colorMode;
+                $mayHaveOptionalAlpha = false;
+        }
+
+        $containsVar = false;
+        $containsNone = false;
+        $isLegacySyntax = false;
+        $expectedArgumentCount = $parserState->strlen($colorModeForParsing);
+        for ($argumentIndex = 0; $argumentIndex < $expectedArgumentCount; ++$argumentIndex) {
+            $parserState->consumeWhiteSpace();
+            $valueKey = $colorModeForParsing[$argumentIndex];
+            if ($parserState->comes('var')) {
+                $colorValues[$valueKey] = CSSFunction::parseIdentifierOrFunction($parserState);
+                $containsVar = true;
+            } elseif (!$isLegacySyntax && $parserState->comes('none')) {
+                $colorValues[$valueKey] = $parserState->parseIdentifier();
+                $containsNone = true;
+            } else {
+                $colorValues[$valueKey] = Size::parse($parserState, true);
+            }
+
+            // This must be done first, to consume comments as well, so that the `comes` test will work.
+            $parserState->consumeWhiteSpace();
+
+            // With a `var` argument, the function can have fewer arguments.
+            // And as of CSS Color Module Level 4, the alpha argument is optional.
+            $canCloseNow =
+                $containsVar
+                || ($mayHaveOptionalAlpha && $argumentIndex >= $expectedArgumentCount - 2);
+            if ($canCloseNow && $parserState->comes(')')) {
+                break;
+            }
+
+            // "Legacy" syntax is comma-delimited, and does not allow the `none` keyword.
+            // "Modern" syntax is space-delimited, with `/` as alpha delimiter.
+            // They cannot be mixed.
+            if ($argumentIndex === 0 && !$containsNone) {
+                // An immediate closing parenthesis is not valid.
+                if ($parserState->comes(')')) {
+                    throw new UnexpectedTokenException(
+                        'Color function with no arguments',
+                        '',
+                        'custom',
+                        $parserState->currentLine()
+                    );
+                }
+                $isLegacySyntax = $parserState->comes(',');
+            }
+
+            if ($isLegacySyntax && $argumentIndex < ($expectedArgumentCount - 1)) {
+                $parserState->consume(',');
+            }
+
+            // In the "modern" syntax, the alpha value must be delimited with `/`.
+            if (!$isLegacySyntax) {
+                if ($containsVar) {
+                    // If the `var` substitution encompasses more than one argument,
+                    // the alpha deliminator may come at any time.
+                    if ($parserState->comes('/')) {
+                        $parserState->consume('/');
+                    }
+                } elseif (($colorModeForParsing[$argumentIndex + 1] ?? '') === 'a') {
+                    // Alpha value is the next expected argument.
+                    // Since a closing parenthesis was not found, a `/` separator is now required.
+                    $parserState->consume('/');
+                }
+            }
+        }
+        $parserState->consume(')');
+
+        return $containsVar
+            ? new CSSFunction($colorMode, \array_values($colorValues), ',', $parserState->currentLine())
+            : new Color($colorValues, $parserState->currentLine());
+    }
+
+    private static function mapRange(float $value, float $fromMin, float $fromMax, float $toMin, float $toMax): float
+    {
+        $fromRange = $fromMax - $fromMin;
+        $toRange = $toMax - $toMin;
+        $multiplier = $toRange / $fromRange;
+        $newValue = $value - $fromMin;
+        $newValue *= $multiplier;
+
+        return $newValue + $toMin;
+    }
+
+    /**
+     * @return array<non-empty-string, Value|string>
+     */
+    public function getColor(): array
+    {
+        return $this->components;
+    }
+
+    /**
+     * @param array<non-empty-string, Value|string> $colorValues
+     */
+    public function setColor(array $colorValues): void
+    {
+        $this->setName(\implode('', \array_keys($colorValues)));
+        $this->components = $colorValues;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function getColorDescription(): string
+    {
+        return $this->getName();
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        if ($this->shouldRenderAsHex($outputFormat)) {
+            return $this->renderAsHex();
+        }
+
+        if ($this->shouldRenderInModernSyntax()) {
+            return $this->renderInModernSyntax($outputFormat);
+        }
+
+        return parent::render($outputFormat);
+    }
+
+    private function shouldRenderAsHex(OutputFormat $outputFormat): bool
+    {
+        return
+            $outputFormat->usesRgbHashNotation()
+            && $this->getRealName() === 'rgb'
+            && $this->allComponentsAreNumbers();
+    }
+
+    /**
+     * The function name is a concatenation of the array keys of the components, which is passed to the constructor.
+     * However, this can be changed by calling {@see CSSFunction::setName},
+     * so is not reliable in situations where it's necessary to determine the function name based on the components.
+     */
+    private function getRealName(): string
+    {
+        return \implode('', \array_keys($this->components));
+    }
+
+    /**
+     * Test whether all color components are absolute numbers (CSS type `number`), not percentages or anything else.
+     * If any component is not an instance of `Size`, the method will also return `false`.
+     */
+    private function allComponentsAreNumbers(): bool
+    {
+        foreach ($this->components as $component) {
+            if (!($component instanceof Size) || $component->getUnit() !== null) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Note that this method assumes the following:
+     * - The `components` array has keys for `r`, `g` and `b`;
+     * - The values in the array are all instances of `Size`.
+     *
+     * Errors will be triggered or thrown if this is not the case.
+     *
+     * @return non-empty-string
+     */
+    private function renderAsHex(): string
+    {
+        $result = \sprintf(
+            '%02x%02x%02x',
+            $this->components['r']->getSize(),
+            $this->components['g']->getSize(),
+            $this->components['b']->getSize()
+        );
+        $canUseShortVariant = ($result[0] === $result[1]) && ($result[2] === $result[3]) && ($result[4] === $result[5]);
+
+        return '#' . ($canUseShortVariant ? $result[0] . $result[2] . $result[4] : $result);
+    }
+
+    /**
+     * The "legacy" syntax does not allow RGB colors to have a mixture of `percentage`s and `number`s,
+     * and does not allow `none` as any component value.
+     *
+     * The "legacy" and "modern" monikers are part of the formal W3C syntax.
+     * See the following for more information:
+     * - {@link
+     *     https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/rgb#formal_syntax
+     *     Description of the formal syntax for `rgb()` on MDN
+     *   };
+     * - {@link
+     *     https://www.w3.org/TR/css-color-4/#rgb-functions
+     *     The same in the CSS Color Module Level 4 W3C Candidate Recommendation Draft
+     *   } (as of 13 February 2024, at time of writing).
+     */
+    private function shouldRenderInModernSyntax(): bool
+    {
+        if ($this->hasNoneAsComponentValue()) {
+            return true;
+        }
+
+        if (!$this->colorFunctionMayHaveMixedValueTypes($this->getRealName())) {
+            return false;
+        }
+
+        $hasPercentage = false;
+        $hasNumber = false;
+        foreach ($this->components as $key => $value) {
+            if ($key === 'a') {
+                // Alpha can have units that don't match those of the RGB components in the "legacy" syntax.
+                // So it is not necessary to check it.  It's also always last, hence `break` rather than `continue`.
+                break;
+            }
+            if (!($value instanceof Size)) {
+                // Unexpected, unknown, or modified via the API
+                return false;
+            }
+            $unit = $value->getUnit();
+            // `switch` only does loose comparison
+            if ($unit === null) {
+                $hasNumber = true;
+            } elseif ($unit === '%') {
+                $hasPercentage = true;
+            } else {
+                // Invalid unit
+                return false;
+            }
+        }
+
+        return $hasPercentage && $hasNumber;
+    }
+
+    private function hasNoneAsComponentValue(): bool
+    {
+        return \in_array('none', $this->components, true);
+    }
+
+    /**
+     * Some color functions, such as `rgb`,
+     * may have a mixture of `percentage`, `number`, or possibly other types in their arguments.
+     *
+     * Note that this excludes the alpha component, which is treated separately.
+     */
+    private function colorFunctionMayHaveMixedValueTypes(string $function): bool
+    {
+        $functionsThatMayHaveMixedValueTypes = ['rgb', 'rgba'];
+
+        return \in_array($function, $functionsThatMayHaveMixedValueTypes, true);
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    private function renderInModernSyntax(OutputFormat $outputFormat): string
+    {
+        // Maybe not yet without alpha, but will be...
+        $componentsWithoutAlpha = $this->components;
+        \end($componentsWithoutAlpha);
+        if (\key($componentsWithoutAlpha) === 'a') {
+            $alpha = $this->components['a'];
+            unset($componentsWithoutAlpha['a']);
+        }
+
+        $formatter = $outputFormat->getFormatter();
+        $arguments = $formatter->implode(' ', $componentsWithoutAlpha);
+        if (isset($alpha)) {
+            $separator = $formatter->spaceBeforeListArgumentSeparator('/')
+                . '/' . $formatter->spaceAfterListArgumentSeparator('/');
+            $arguments = $formatter->implode($separator, [$arguments, $alpha]);
+        }
+
+        return $this->getName() . '(' . $arguments . ')';
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/LineName.php b/includes/Dependencies/Sabberworm/CSS/Value/LineName.php
new file mode 100644
index 0000000..74cbd0b
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/LineName.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+class LineName extends ValueList
+{
+    /**
+     * @param array<Value|string> $components
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(array $components = [], ?int $lineNumber = null)
+    {
+        parent::__construct($components, ' ', $lineNumber);
+    }
+
+    /**
+     * @throws UnexpectedTokenException
+     * @throws UnexpectedEOFException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState): LineName
+    {
+        $parserState->consume('[');
+        $parserState->consumeWhiteSpace();
+        $names = [];
+        do {
+            if ($parserState->getSettings()->usesLenientParsing()) {
+                try {
+                    $names[] = $parserState->parseIdentifier();
+                } catch (UnexpectedTokenException $e) {
+                    if (!$parserState->comes(']')) {
+                        throw $e;
+                    }
+                }
+            } else {
+                $names[] = $parserState->parseIdentifier();
+            }
+            $parserState->consumeWhiteSpace();
+        } while (!$parserState->comes(']'));
+        $parserState->consume(']');
+        return new LineName($names, $parserState->currentLine());
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return '[' . parent::render(OutputFormat::createCompact()) . ']';
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/PrimitiveValue.php b/includes/Dependencies/Sabberworm/CSS/Value/PrimitiveValue.php
new file mode 100644
index 0000000..269805d
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/PrimitiveValue.php
@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+abstract class PrimitiveValue extends Value {}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/RuleValueList.php b/includes/Dependencies/Sabberworm/CSS/Value/RuleValueList.php
new file mode 100644
index 0000000..418fbcd
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/RuleValueList.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+/**
+ * This class is used to represent all multivalued rules like `font: bold 12px/3 Helvetica, Verdana, sans-serif;`
+ * (where the value would be a whitespace-separated list of the primitive value `bold`, a slash-separated list
+ * and a comma-separated list).
+ */
+class RuleValueList extends ValueList
+{
+    /**
+     * @param non-empty-string $separator
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(string $separator = ',', ?int $lineNumber = null)
+    {
+        parent::__construct([], $separator, $lineNumber);
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/Size.php b/includes/Dependencies/Sabberworm/CSS/Value/Size.php
new file mode 100644
index 0000000..4a8eb3a
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/Size.php
@@ -0,0 +1,210 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+/**
+ * A `Size` consists of a numeric `size` value and a unit.
+ */
+class Size extends PrimitiveValue
+{
+    /**
+     * vh/vw/vm(ax)/vmin/rem are absolute insofar as they don’t scale to the immediate parent (only the viewport)
+     *
+     * @var list<non-empty-string>
+     */
+    private const ABSOLUTE_SIZE_UNITS = [
+        'px',
+        'pt',
+        'pc',
+        'cm',
+        'mm',
+        'mozmm',
+        'in',
+        'vh',
+        'dvh',
+        'svh',
+        'lvh',
+        'vw',
+        'vmin',
+        'vmax',
+        'rem',
+    ];
+
+    /**
+     * @var list<non-empty-string>
+     */
+    private const RELATIVE_SIZE_UNITS = ['%', 'em', 'ex', 'ch', 'fr'];
+
+    /**
+     * @var list<non-empty-string>
+     */
+    private const NON_SIZE_UNITS = ['deg', 'grad', 'rad', 's', 'ms', 'turn', 'Hz', 'kHz'];
+
+    /**
+     * @var array<int<1, max>, array<lowercase-string, non-empty-string>>|null
+     */
+    private static $SIZE_UNITS = null;
+
+    /**
+     * @var float
+     */
+    private $size;
+
+    /**
+     * @var string|null
+     */
+    private $unit;
+
+    /**
+     * @var bool
+     */
+    private $isColorComponent;
+
+    /**
+     * @param float|int|string $size
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct($size, ?string $unit = null, bool $isColorComponent = false, ?int $lineNumber = null)
+    {
+        parent::__construct($lineNumber);
+        $this->size = (float) $size;
+        $this->unit = $unit;
+        $this->isColorComponent = $isColorComponent;
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState, bool $isColorComponent = false): Size
+    {
+        $size = '';
+        if ($parserState->comes('-')) {
+            $size .= $parserState->consume('-');
+        }
+        while (\is_numeric($parserState->peek()) || $parserState->comes('.') || $parserState->comes('e', true)) {
+            if ($parserState->comes('.')) {
+                $size .= $parserState->consume('.');
+            } elseif ($parserState->comes('e', true)) {
+                $lookahead = $parserState->peek(1, 1);
+                if (\is_numeric($lookahead) || $lookahead === '+' || $lookahead === '-') {
+                    $size .= $parserState->consume(2);
+                } else {
+                    break; // Reached the unit part of the number like "em" or "ex"
+                }
+            } else {
+                $size .= $parserState->consume(1);
+            }
+        }
+
+        $unit = null;
+        $sizeUnits = self::getSizeUnits();
+        foreach ($sizeUnits as $length => &$values) {
+            $key = \strtolower($parserState->peek($length));
+            if (\array_key_exists($key, $values)) {
+                if (($unit = $values[$key]) !== null) {
+                    $parserState->consume($length);
+                    break;
+                }
+            }
+        }
+        return new Size((float) $size, $unit, $isColorComponent, $parserState->currentLine());
+    }
+
+    /**
+     * @return array<int<1, max>, array<lowercase-string, non-empty-string>>
+     */
+    private static function getSizeUnits(): array
+    {
+        if (!\is_array(self::$SIZE_UNITS)) {
+            self::$SIZE_UNITS = [];
+            $sizeUnits = \array_merge(self::ABSOLUTE_SIZE_UNITS, self::RELATIVE_SIZE_UNITS, self::NON_SIZE_UNITS);
+            foreach ($sizeUnits as $sizeUnit) {
+                $tokenLength = \strlen($sizeUnit);
+                if (!isset(self::$SIZE_UNITS[$tokenLength])) {
+                    self::$SIZE_UNITS[$tokenLength] = [];
+                }
+                self::$SIZE_UNITS[$tokenLength][\strtolower($sizeUnit)] = $sizeUnit;
+            }
+
+            \krsort(self::$SIZE_UNITS, SORT_NUMERIC);
+        }
+
+        return self::$SIZE_UNITS;
+    }
+
+    public function setUnit(string $unit): void
+    {
+        $this->unit = $unit;
+    }
+
+    public function getUnit(): ?string
+    {
+        return $this->unit;
+    }
+
+    /**
+     * @param float|int|string $size
+     */
+    public function setSize($size): void
+    {
+        $this->size = (float) $size;
+    }
+
+    public function getSize(): float
+    {
+        return $this->size;
+    }
+
+    public function isColorComponent(): bool
+    {
+        return $this->isColorComponent;
+    }
+
+    /**
+     * Returns whether the number stored in this Size really represents a size (as in a length of something on screen).
+     *
+     * Returns `false` if the unit is an angle, a duration, a frequency, or the number is a component in a `Color`
+     * object.
+     */
+    public function isSize(): bool
+    {
+        if (\in_array($this->unit, self::NON_SIZE_UNITS, true)) {
+            return false;
+        }
+        return !$this->isColorComponent();
+    }
+
+    public function isRelative(): bool
+    {
+        if (\in_array($this->unit, self::RELATIVE_SIZE_UNITS, true)) {
+            return true;
+        }
+        if ($this->unit === null && $this->size !== 0.0) {
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        $locale = \localeconv();
+        $decimalPoint = \preg_quote($locale['decimal_point'], '/');
+        $size = \preg_match('/[\\d\\.]+e[+-]?\\d+/i', (string) $this->size)
+            ? \preg_replace("/$decimalPoint?0+$/", '', \sprintf('%f', $this->size)) : (string) $this->size;
+
+        return \preg_replace(["/$decimalPoint/", '/^(-?)0\\./'], ['.', '$1.'], $size) . ($this->unit ?? '');
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/URL.php b/includes/Dependencies/Sabberworm/CSS/Value/URL.php
new file mode 100644
index 0000000..25dea62
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/URL.php
@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+
+/**
+ * This class represents URLs in CSS. `URL`s always output in `URL("")` notation.
+ */
+class URL extends PrimitiveValue
+{
+    /**
+     * @var CSSString
+     */
+    private $url;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(CSSString $url, ?int $lineNumber = null)
+    {
+        parent::__construct($lineNumber);
+        $this->url = $url;
+    }
+
+    /**
+     * @throws SourceException
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parse(ParserState $parserState): URL
+    {
+        $anchor = $parserState->anchor();
+        $identifier = '';
+        for ($i = 0; $i < 3; $i++) {
+            $character = $parserState->parseCharacter(true);
+            if ($character === null) {
+                break;
+            }
+            $identifier .= $character;
+        }
+        $useUrl = $parserState->streql($identifier, 'url');
+        if ($useUrl) {
+            $parserState->consumeWhiteSpace();
+            $parserState->consume('(');
+        } else {
+            $anchor->backtrack();
+        }
+        $parserState->consumeWhiteSpace();
+        $result = new URL(CSSString::parse($parserState), $parserState->currentLine());
+        if ($useUrl) {
+            $parserState->consumeWhiteSpace();
+            $parserState->consume(')');
+        }
+        return $result;
+    }
+
+    public function setURL(CSSString $url): void
+    {
+        $this->url = $url;
+    }
+
+    public function getURL(): CSSString
+    {
+        return $this->url;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function render(OutputFormat $outputFormat): string
+    {
+        return "url({$this->url->render($outputFormat)})";
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/Value.php b/includes/Dependencies/Sabberworm/CSS/Value/Value.php
new file mode 100644
index 0000000..ecb19dd
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/Value.php
@@ -0,0 +1,211 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\CSSElement;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\ParserState;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\SourceException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedEOFException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Parsing\UnexpectedTokenException;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Position;
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Position\Positionable;
+
+/**
+ * Abstract base class for specific classes of CSS values: `Size`, `Color`, `CSSString` and `URL`, and another
+ * abstract subclass `ValueList`.
+ */
+abstract class Value implements CSSElement, Positionable
+{
+    use Position;
+
+    /**
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct(?int $lineNumber = null)
+    {
+        $this->setPosition($lineNumber);
+    }
+
+    /**
+     * @param array<non-empty-string> $listDelimiters
+     *
+     * @return Value|string
+     *
+     * @throws UnexpectedTokenException
+     * @throws UnexpectedEOFException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parseValue(ParserState $parserState, array $listDelimiters = [])
+    {
+        /** @var list<Value|string> $stack */
+        $stack = [];
+        $parserState->consumeWhiteSpace();
+        //Build a list of delimiters and parsed values
+        while (
+        !($parserState->comes('}') || $parserState->comes(';') || $parserState->comes('!')
+            || $parserState->comes(')')
+            || $parserState->isEnd())
+        ) {
+            if (\count($stack) > 0) {
+                $foundDelimiter = false;
+                foreach ($listDelimiters as $delimiter) {
+                    if ($parserState->comes($delimiter)) {
+                        \array_push($stack, $parserState->consume($delimiter));
+                        $parserState->consumeWhiteSpace();
+                        $foundDelimiter = true;
+                        break;
+                    }
+                }
+                if (!$foundDelimiter) {
+                    //Whitespace was the list delimiter
+                    \array_push($stack, ' ');
+                }
+            }
+            \array_push($stack, self::parsePrimitiveValue($parserState));
+            $parserState->consumeWhiteSpace();
+        }
+        // Convert the list to list objects
+        foreach ($listDelimiters as $delimiter) {
+            $stackSize = \count($stack);
+            if ($stackSize === 1) {
+                return $stack[0];
+            }
+            $newStack = [];
+            for ($offset = 0; $offset < $stackSize; ++$offset) {
+                if ($offset === ($stackSize - 1) || $delimiter !== $stack[$offset + 1]) {
+                    $newStack[] = $stack[$offset];
+                    continue;
+                }
+                $length = 2; //Number of elements to be joined
+                for ($i = $offset + 3; $i < $stackSize; $i += 2, ++$length) {
+                    if ($delimiter !== $stack[$i]) {
+                        break;
+                    }
+                }
+                $list = new RuleValueList($delimiter, $parserState->currentLine());
+                for ($i = $offset; $i - $offset < $length * 2; $i += 2) {
+                    $list->addListComponent($stack[$i]);
+                }
+                $newStack[] = $list;
+                $offset += $length * 2 - 2;
+            }
+            $stack = $newStack;
+        }
+        if (!isset($stack[0])) {
+            throw new UnexpectedTokenException(
+                " {$parserState->peek()} ",
+                $parserState->peek(1, -1) . $parserState->peek(2),
+                'literal',
+                $parserState->currentLine()
+            );
+        }
+        return $stack[0];
+    }
+
+    /**
+     * @return CSSFunction|string
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parseIdentifierOrFunction(ParserState $parserState, bool $ignoreCase = false)
+    {
+        $anchor = $parserState->anchor();
+        $result = $parserState->parseIdentifier($ignoreCase);
+
+        if ($parserState->comes('(')) {
+            $anchor->backtrack();
+            if ($parserState->streql('url', $result)) {
+                $result = URL::parse($parserState);
+            } elseif ($parserState->streql('calc', $result)) {
+                $result = CalcFunction::parse($parserState);
+            } else {
+                $result = CSSFunction::parse($parserState, $ignoreCase);
+            }
+        }
+
+        return $result;
+    }
+
+    /**
+     * @return CSSFunction|CSSString|LineName|Size|URL|string
+     *
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     * @throws SourceException
+     *
+     * @internal since V8.8.0
+     */
+    public static function parsePrimitiveValue(ParserState $parserState)
+    {
+        $value = null;
+        $parserState->consumeWhiteSpace();
+        if (
+            \is_numeric($parserState->peek())
+            || ($parserState->comes('-.')
+                && \is_numeric($parserState->peek(1, 2)))
+            || (($parserState->comes('-') || $parserState->comes('.')) && \is_numeric($parserState->peek(1, 1)))
+        ) {
+            $value = Size::parse($parserState);
+        } elseif ($parserState->comes('#') || $parserState->comes('rgb', true) || $parserState->comes('hsl', true)) {
+            $value = Color::parse($parserState);
+        } elseif ($parserState->comes("'") || $parserState->comes('"')) {
+            $value = CSSString::parse($parserState);
+        } elseif ($parserState->comes('progid:') && $parserState->getSettings()->usesLenientParsing()) {
+            $value = self::parseMicrosoftFilter($parserState);
+        } elseif ($parserState->comes('[')) {
+            $value = LineName::parse($parserState);
+        } elseif ($parserState->comes('U+')) {
+            $value = self::parseUnicodeRangeValue($parserState);
+        } else {
+            $nextCharacter = $parserState->peek(1);
+            try {
+                $value = self::parseIdentifierOrFunction($parserState);
+            } catch (UnexpectedTokenException $e) {
+                if (\in_array($nextCharacter, ['+', '-', '*', '/'], true)) {
+                    $value = $parserState->consume(1);
+                } else {
+                    throw $e;
+                }
+            }
+        }
+        $parserState->consumeWhiteSpace();
+
+        return $value;
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseMicrosoftFilter(ParserState $parserState): CSSFunction
+    {
+        $function = $parserState->consumeUntil('(', false, true);
+        $arguments = Value::parseValue($parserState, [',', '=']);
+        return new CSSFunction($function, $arguments, ',', $parserState->currentLine());
+    }
+
+    /**
+     * @throws UnexpectedEOFException
+     * @throws UnexpectedTokenException
+     */
+    private static function parseUnicodeRangeValue(ParserState $parserState): string
+    {
+        $codepointMaxLength = 6; // Code points outside BMP can use up to six digits
+        $range = '';
+        $parserState->consume('U+');
+        do {
+            if ($parserState->comes('-')) {
+                $codepointMaxLength = 13; // Max length is 2 six-digit code points + the dash(-) between them
+            }
+            $range .= $parserState->consume(1);
+        } while (\strlen($range) < $codepointMaxLength && \preg_match('/[A-Fa-f0-9\\?-]/', $parserState->peek()));
+
+        return "U+{$range}";
+    }
+}
diff --git a/includes/Dependencies/Sabberworm/CSS/Value/ValueList.php b/includes/Dependencies/Sabberworm/CSS/Value/ValueList.php
new file mode 100644
index 0000000..0f8a162
--- /dev/null
+++ b/includes/Dependencies/Sabberworm/CSS/Value/ValueList.php
@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eighteen73\Orbit\Dependencies\Sabberworm\CSS\Value;
+
+use Eighteen73\Orbit\Dependencies\Sabberworm\CSS\OutputFormat;
+
+/**
+ * A `ValueList` represents a lists of `Value`s, separated by some separation character
+ * (mostly `,`, whitespace, or `/`).
+ *
+ * There are two types of `ValueList`s: `RuleValueList` and `CSSFunction`
+ */
+abstract class ValueList extends Value
+{
+    /**
+     * @var array<Value|string>
+     *
+     * @internal since 8.8.0
+     */
+    protected $components;
+
+    /**
+     * @var non-empty-string
+     *
+     * @internal since 8.8.0
+     */
+    protected $separator;
+
+    /**
+     * @param array<Value|string>|Value|string $components
+     * @param non-empty-string $separator
+     * @param int<1, max>|null $lineNumber
+     */
+    public function __construct($components = [], $separator = ',', ?int $lineNumber = null)
+    {
+        parent::__construct($lineNumber);
+        if (!\is_array($components)) {
+            $components = [$components];
+        }
+        $this->components = $components;
+        $this->separator = $separator;
+    }
+
+    /**
+     * @param Value|string $component
+     */
+    public function addListComponent($component): void
+    {
+        $this->components[] = $component;
+    }
+
+    /**
+     * @return array<Value|string>
+     */
+    public function getListComponents(): array
+    {
+        return $this->components;
+    }
+
+    /**
+     * @param array<Value|string> $components
+     */
+    public function setListComponents(array $components): void
+    {
+        $this->components = $components;
+    }
+
+    /**
+     * @return non-empty-string
+     */
+    public function getListSeparator(): string
+    {
+        return $this->separator;
+    }
+
+    /**
+     * @param non-empty-string $separator
+     */
+    public function setListSeparator(string $separator): void
+    {
+        $this->separator = $separator;
+    }
+
+    public function render(OutputFormat $outputFormat): string
+    {
+        $formatter = $outputFormat->getFormatter();
+
+        return $formatter->implode(
+            $formatter->spaceBeforeListArgumentSeparator($this->separator) . $this->separator
+            . $formatter->spaceAfterListArgumentSeparator($this->separator),
+            $this->components
+        );
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/CHANGELOG.md b/includes/Dependencies/Symfony/Component/CssSelector/CHANGELOG.md
new file mode 100644
index 0000000..d2b7fb1
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/CHANGELOG.md
@@ -0,0 +1,29 @@
+CHANGELOG
+=========
+
+7.1
+---
+
+ * Add support for `:is()`
+ * Add support for `:where()`
+
+6.3
+---
+
+ * Add support for `:scope`
+
+4.4.0
+-----
+
+ * Added support for `*:only-of-type`
+
+2.8.0
+-----
+
+ * Added the `CssSelectorConverter` class as a non-static API for the component.
+ * Deprecated the `CssSelector` static API of the component.
+
+2.1.0
+-----
+
+ * none
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/CssSelectorConverter.php b/includes/Dependencies/Symfony/Component/CssSelector/CssSelectorConverter.php
new file mode 100644
index 0000000..c1d0305
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/CssSelectorConverter.php
@@ -0,0 +1,67 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut\ClassParser;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut\ElementParser;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut\EmptyStringParser;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut\HashParser;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension\HtmlExtension;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Translator;
+
+/**
+ * CssSelectorConverter is the main entry point of the component and can convert CSS
+ * selectors to XPath expressions.
+ *
+ * @author Christophe Coevoet <stof@notk.org>
+ */
+class CssSelectorConverter
+{
+    private Translator $translator;
+    private array $cache;
+
+    private static array $xmlCache = [];
+    private static array $htmlCache = [];
+
+    /**
+     * @param bool $html Whether HTML support should be enabled. Disable it for XML documents
+     */
+    public function __construct(bool $html = true)
+    {
+        $this->translator = new Translator();
+
+        if ($html) {
+            $this->translator->registerExtension(new HtmlExtension($this->translator));
+            $this->cache = &self::$htmlCache;
+        } else {
+            $this->cache = &self::$xmlCache;
+        }
+
+        $this->translator
+            ->registerParserShortcut(new EmptyStringParser())
+            ->registerParserShortcut(new ElementParser())
+            ->registerParserShortcut(new ClassParser())
+            ->registerParserShortcut(new HashParser())
+        ;
+    }
+
+    /**
+     * Translates a CSS expression to its XPath equivalent.
+     *
+     * Optionally, a prefix can be added to the resulting XPath
+     * expression with the $prefix parameter.
+     */
+    public function toXPath(string $cssExpr, string $prefix = 'descendant-or-self::'): string
+    {
+        return $this->cache[$prefix][$cssExpr] ??= $this->translator->cssToXPath($cssExpr, $prefix);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Exception/ExceptionInterface.php b/includes/Dependencies/Symfony/Component/CssSelector/Exception/ExceptionInterface.php
new file mode 100644
index 0000000..93a079c
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Exception/ExceptionInterface.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception;
+
+/**
+ * Interface for exceptions.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ */
+interface ExceptionInterface extends \Throwable
+{
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Exception/ExpressionErrorException.php b/includes/Dependencies/Symfony/Component/CssSelector/Exception/ExpressionErrorException.php
new file mode 100644
index 0000000..62a5ed5
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Exception/ExpressionErrorException.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception;
+
+/**
+ * ParseException is thrown when a CSS selector syntax is not valid.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ */
+class ExpressionErrorException extends ParseException
+{
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Exception/InternalErrorException.php b/includes/Dependencies/Symfony/Component/CssSelector/Exception/InternalErrorException.php
new file mode 100644
index 0000000..1b848ea
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Exception/InternalErrorException.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception;
+
+/**
+ * ParseException is thrown when a CSS selector syntax is not valid.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ */
+class InternalErrorException extends ParseException
+{
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Exception/ParseException.php b/includes/Dependencies/Symfony/Component/CssSelector/Exception/ParseException.php
new file mode 100644
index 0000000..4e85d2f
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Exception/ParseException.php
@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception;
+
+/**
+ * ParseException is thrown when a CSS selector syntax is not valid.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class ParseException extends \Exception implements ExceptionInterface
+{
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Exception/SyntaxErrorException.php b/includes/Dependencies/Symfony/Component/CssSelector/Exception/SyntaxErrorException.php
new file mode 100644
index 0000000..5cfd48d
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Exception/SyntaxErrorException.php
@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+
+/**
+ * ParseException is thrown when a CSS selector syntax is not valid.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ */
+class SyntaxErrorException extends ParseException
+{
+    public static function unexpectedToken(string $expectedValue, Token $foundToken): self
+    {
+        return new self(\sprintf('Expected %s, but %s found.', $expectedValue, $foundToken));
+    }
+
+    public static function pseudoElementFound(string $pseudoElement, string $unexpectedLocation): self
+    {
+        return new self(\sprintf('Unexpected pseudo-element "::%s" found %s.', $pseudoElement, $unexpectedLocation));
+    }
+
+    public static function unclosedString(int $position): self
+    {
+        return new self(\sprintf('Unclosed/invalid string at %s.', $position));
+    }
+
+    public static function nestedNot(): self
+    {
+        return new self('Got nested ::not().');
+    }
+
+    public static function notAtTheStartOfASelector(string $pseudoElement): self
+    {
+        return new self(\sprintf('Got immediate child pseudo-element ":%s" not at the start of a selector', $pseudoElement));
+    }
+
+    public static function stringAsFunctionArgument(): self
+    {
+        return new self('String not allowed as function argument.');
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/LICENSE b/includes/Dependencies/Symfony/Component/CssSelector/LICENSE
new file mode 100644
index 0000000..0138f8f
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2004-present Fabien Potencier
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is furnished
+to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/AbstractNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/AbstractNode.php
new file mode 100644
index 0000000..879565d
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/AbstractNode.php
@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Abstract base node class.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+abstract class AbstractNode implements NodeInterface
+{
+    private string $nodeName;
+
+    public function getNodeName(): string
+    {
+        return $this->nodeName ??= preg_replace('~.*\\\\([^\\\\]+)Node$~', '$1', static::class);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/AttributeNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/AttributeNode.php
new file mode 100644
index 0000000..55ff691
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/AttributeNode.php
@@ -0,0 +1,73 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>[<namespace>|<attribute> <operator> <value>]" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class AttributeNode extends AbstractNode
+{
+    public function __construct(
+        private NodeInterface $selector,
+        private ?string $namespace,
+        private string $attribute,
+        private string $operator,
+        private ?string $value,
+    ) {
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getNamespace(): ?string
+    {
+        return $this->namespace;
+    }
+
+    public function getAttribute(): string
+    {
+        return $this->attribute;
+    }
+
+    public function getOperator(): string
+    {
+        return $this->operator;
+    }
+
+    public function getValue(): ?string
+    {
+        return $this->value;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus(new Specificity(0, 1, 0));
+    }
+
+    public function __toString(): string
+    {
+        $attribute = $this->namespace ? $this->namespace.'|'.$this->attribute : $this->attribute;
+
+        return 'exists' === $this->operator
+            ? \sprintf('%s[%s[%s]]', $this->getNodeName(), $this->selector, $attribute)
+            : \sprintf("%s[%s[%s %s '%s']]", $this->getNodeName(), $this->selector, $attribute, $this->operator, $this->value);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/ClassNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/ClassNode.php
new file mode 100644
index 0000000..c5680f7
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/ClassNode.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>.<name>" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class ClassNode extends AbstractNode
+{
+    public function __construct(
+        private NodeInterface $selector,
+        private string $name,
+    ) {
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus(new Specificity(0, 1, 0));
+    }
+
+    public function __toString(): string
+    {
+        return \sprintf('%s[%s.%s]', $this->getNodeName(), $this->selector, $this->name);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/CombinedSelectorNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/CombinedSelectorNode.php
new file mode 100644
index 0000000..e7c0c1c
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/CombinedSelectorNode.php
@@ -0,0 +1,59 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a combined node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class CombinedSelectorNode extends AbstractNode
+{
+    public function __construct(
+        private NodeInterface $selector,
+        private string $combinator,
+        private NodeInterface $subSelector,
+    ) {
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getCombinator(): string
+    {
+        return $this->combinator;
+    }
+
+    public function getSubSelector(): NodeInterface
+    {
+        return $this->subSelector;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus($this->subSelector->getSpecificity());
+    }
+
+    public function __toString(): string
+    {
+        $combinator = ' ' === $this->combinator ? '<followed>' : $this->combinator;
+
+        return \sprintf('%s[%s %s %s]', $this->getNodeName(), $this->selector, $combinator, $this->subSelector);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/ElementNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/ElementNode.php
new file mode 100644
index 0000000..9ddf19e
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/ElementNode.php
@@ -0,0 +1,53 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<namespace>|<element>" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class ElementNode extends AbstractNode
+{
+    public function __construct(
+        private ?string $namespace = null,
+        private ?string $element = null,
+    ) {
+    }
+
+    public function getNamespace(): ?string
+    {
+        return $this->namespace;
+    }
+
+    public function getElement(): ?string
+    {
+        return $this->element;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return new Specificity(0, 0, $this->element ? 1 : 0);
+    }
+
+    public function __toString(): string
+    {
+        $element = $this->element ?: '*';
+
+        return \sprintf('%s[%s]', $this->getNodeName(), $this->namespace ? $this->namespace.'|'.$element : $element);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/FunctionNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/FunctionNode.php
new file mode 100644
index 0000000..8083d3b
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/FunctionNode.php
@@ -0,0 +1,70 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+
+/**
+ * Represents a "<selector>:<name>(<arguments>)" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class FunctionNode extends AbstractNode
+{
+    private string $name;
+
+    /**
+     * @param Token[] $arguments
+     */
+    public function __construct(
+        private NodeInterface $selector,
+        string $name,
+        private array $arguments = [],
+    ) {
+        $this->name = strtolower($name);
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    /**
+     * @return Token[]
+     */
+    public function getArguments(): array
+    {
+        return $this->arguments;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus(new Specificity(0, 1, 0));
+    }
+
+    public function __toString(): string
+    {
+        $arguments = implode(', ', array_map(fn (Token $token) => "'".$token->getValue()."'", $this->arguments));
+
+        return \sprintf('%s[%s:%s(%s)]', $this->getNodeName(), $this->selector, $this->name, $arguments ? '['.$arguments.']' : '');
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/HashNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/HashNode.php
new file mode 100644
index 0000000..259a3cb
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/HashNode.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>#<id>" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class HashNode extends AbstractNode
+{
+    public function __construct(
+        private NodeInterface $selector,
+        private string $id,
+    ) {
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getId(): string
+    {
+        return $this->id;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus(new Specificity(1, 0, 0));
+    }
+
+    public function __toString(): string
+    {
+        return \sprintf('%s[%s#%s]', $this->getNodeName(), $this->selector, $this->id);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/MatchingNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/MatchingNode.php
new file mode 100644
index 0000000..eddd2a5
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/MatchingNode.php
@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>:is(<subSelectorList>)" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Hubert Lenoir <lenoir.hubert@gmail.com>
+ *
+ * @internal
+ */
+class MatchingNode extends AbstractNode
+{
+    /**
+     * @param array<NodeInterface> $arguments
+     */
+    public function __construct(
+        public readonly NodeInterface $selector,
+        public readonly array $arguments = [],
+    ) {
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        $argumentsSpecificity = array_reduce(
+            $this->arguments,
+            fn ($c, $n) => 1 === $n->getSpecificity()->compareTo($c) ? $n->getSpecificity() : $c,
+            new Specificity(0, 0, 0),
+        );
+
+        return $this->selector->getSpecificity()->plus($argumentsSpecificity);
+    }
+
+    public function __toString(): string
+    {
+        $selectorArguments = array_map(
+            fn ($n): string => ltrim((string) $n, '*'),
+            $this->arguments,
+        );
+
+        return \sprintf('%s[%s:is(%s)]', $this->getNodeName(), $this->selector, implode(', ', $selectorArguments));
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/NegationNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/NegationNode.php
new file mode 100644
index 0000000..8cc3633
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/NegationNode.php
@@ -0,0 +1,51 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>:not(<identifier>)" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class NegationNode extends AbstractNode
+{
+    public function __construct(
+        private NodeInterface $selector,
+        private NodeInterface $subSelector,
+    ) {
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getSubSelector(): NodeInterface
+    {
+        return $this->subSelector;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus($this->subSelector->getSpecificity());
+    }
+
+    public function __toString(): string
+    {
+        return \sprintf('%s[%s:not(%s)]', $this->getNodeName(), $this->selector, $this->subSelector);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/NodeInterface.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/NodeInterface.php
new file mode 100644
index 0000000..03bf654
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/NodeInterface.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Interface for nodes.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+interface NodeInterface extends \Stringable
+{
+    public function getNodeName(): string;
+
+    public function getSpecificity(): Specificity;
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/PseudoNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/PseudoNode.php
new file mode 100644
index 0000000..4bc00e6
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/PseudoNode.php
@@ -0,0 +1,54 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>:<identifier>" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class PseudoNode extends AbstractNode
+{
+    private string $identifier;
+
+    public function __construct(
+        private NodeInterface $selector,
+        string $identifier,
+    ) {
+        $this->identifier = strtolower($identifier);
+    }
+
+    public function getSelector(): NodeInterface
+    {
+        return $this->selector;
+    }
+
+    public function getIdentifier(): string
+    {
+        return $this->identifier;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity()->plus(new Specificity(0, 1, 0));
+    }
+
+    public function __toString(): string
+    {
+        return \sprintf('%s[%s:%s]', $this->getNodeName(), $this->selector, $this->identifier);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/SelectorNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/SelectorNode.php
new file mode 100644
index 0000000..110b28b
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/SelectorNode.php
@@ -0,0 +1,54 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>(::|:)<pseudoElement>" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class SelectorNode extends AbstractNode
+{
+    private ?string $pseudoElement;
+
+    public function __construct(
+        private NodeInterface $tree,
+        ?string $pseudoElement = null,
+    ) {
+        $this->pseudoElement = $pseudoElement ? strtolower($pseudoElement) : null;
+    }
+
+    public function getTree(): NodeInterface
+    {
+        return $this->tree;
+    }
+
+    public function getPseudoElement(): ?string
+    {
+        return $this->pseudoElement;
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->tree->getSpecificity()->plus(new Specificity(0, 0, $this->pseudoElement ? 1 : 0));
+    }
+
+    public function __toString(): string
+    {
+        return \sprintf('%s[%s%s]', $this->getNodeName(), $this->tree, $this->pseudoElement ? '::'.$this->pseudoElement : '');
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/Specificity.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/Specificity.php
new file mode 100644
index 0000000..67b775e
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/Specificity.php
@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a node specificity.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @see http://www.w3.org/TR/selectors/#specificity
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class Specificity
+{
+    public const A_FACTOR = 100;
+    public const B_FACTOR = 10;
+    public const C_FACTOR = 1;
+
+    public function __construct(
+        private int $a,
+        private int $b,
+        private int $c,
+    ) {
+    }
+
+    public function plus(self $specificity): self
+    {
+        return new self($this->a + $specificity->a, $this->b + $specificity->b, $this->c + $specificity->c);
+    }
+
+    public function getValue(): int
+    {
+        return $this->a * self::A_FACTOR + $this->b * self::B_FACTOR + $this->c * self::C_FACTOR;
+    }
+
+    /**
+     * Returns -1 if the object specificity is lower than the argument,
+     * 0 if they are equal, and 1 if the argument is lower.
+     */
+    public function compareTo(self $specificity): int
+    {
+        if ($this->a !== $specificity->a) {
+            return $this->a > $specificity->a ? 1 : -1;
+        }
+
+        if ($this->b !== $specificity->b) {
+            return $this->b > $specificity->b ? 1 : -1;
+        }
+
+        if ($this->c !== $specificity->c) {
+            return $this->c > $specificity->c ? 1 : -1;
+        }
+
+        return 0;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Node/SpecificityAdjustmentNode.php b/includes/Dependencies/Symfony/Component/CssSelector/Node/SpecificityAdjustmentNode.php
new file mode 100644
index 0000000..fe835ff
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Node/SpecificityAdjustmentNode.php
@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+
+/**
+ * Represents a "<selector>:where(<subSelectorList>)" node.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Hubert Lenoir <lenoir.hubert@gmail.com>
+ *
+ * @internal
+ */
+class SpecificityAdjustmentNode extends AbstractNode
+{
+    /**
+     * @param array<NodeInterface> $arguments
+     */
+    public function __construct(
+        public readonly NodeInterface $selector,
+        public readonly array $arguments = [],
+    ) {
+    }
+
+    public function getSpecificity(): Specificity
+    {
+        return $this->selector->getSpecificity();
+    }
+
+    public function __toString(): string
+    {
+        $selectorArguments = array_map(
+            fn ($n) => ltrim((string) $n, '*'),
+            $this->arguments,
+        );
+
+        return \sprintf('%s[%s:where(%s)]', $this->getNodeName(), $this->selector, implode(', ', $selectorArguments));
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/CommentHandler.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/CommentHandler.php
new file mode 100644
index 0000000..0c0ecfa
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/CommentHandler.php
@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector comment handler.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class CommentHandler implements HandlerInterface
+{
+    public function handle(Reader $reader, TokenStream $stream): bool
+    {
+        if ('/*' !== $reader->getSubstring(2)) {
+            return false;
+        }
+
+        $offset = $reader->getOffset('*/');
+
+        if (false === $offset) {
+            $reader->moveToEnd();
+        } else {
+            $reader->moveForward($offset + 2);
+        }
+
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HandlerInterface.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HandlerInterface.php
new file mode 100644
index 0000000..431f0a2
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HandlerInterface.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector handler interface.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+interface HandlerInterface
+{
+    public function handle(Reader $reader, TokenStream $stream): bool;
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HashHandler.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HashHandler.php
new file mode 100644
index 0000000..c49ace8
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/HashHandler.php
@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerEscaping;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerPatterns;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector comment handler.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class HashHandler implements HandlerInterface
+{
+    public function __construct(
+        private TokenizerPatterns $patterns,
+        private TokenizerEscaping $escaping,
+    ) {
+    }
+
+    public function handle(Reader $reader, TokenStream $stream): bool
+    {
+        $match = $reader->findPattern($this->patterns->getHashPattern());
+
+        if (!$match) {
+            return false;
+        }
+
+        $value = $this->escaping->escapeUnicode($match[1]);
+        $stream->push(new Token(Token::TYPE_HASH, $value, $reader->getPosition()));
+        $reader->moveForward(\strlen($match[0]));
+
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/IdentifierHandler.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/IdentifierHandler.php
new file mode 100644
index 0000000..e768e2f
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/IdentifierHandler.php
@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerEscaping;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerPatterns;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector comment handler.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class IdentifierHandler implements HandlerInterface
+{
+    public function __construct(
+        private TokenizerPatterns $patterns,
+        private TokenizerEscaping $escaping,
+    ) {
+    }
+
+    public function handle(Reader $reader, TokenStream $stream): bool
+    {
+        $match = $reader->findPattern($this->patterns->getIdentifierPattern());
+
+        if (!$match) {
+            return false;
+        }
+
+        $value = $this->escaping->escapeUnicode($match[0]);
+        $stream->push(new Token(Token::TYPE_IDENTIFIER, $value, $reader->getPosition()));
+        $reader->moveForward(\strlen($match[0]));
+
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/NumberHandler.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/NumberHandler.php
new file mode 100644
index 0000000..7180c44
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/NumberHandler.php
@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerPatterns;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector comment handler.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class NumberHandler implements HandlerInterface
+{
+    public function __construct(
+        private TokenizerPatterns $patterns,
+    ) {
+    }
+
+    public function handle(Reader $reader, TokenStream $stream): bool
+    {
+        $match = $reader->findPattern($this->patterns->getNumberPattern());
+
+        if (!$match) {
+            return false;
+        }
+
+        $stream->push(new Token(Token::TYPE_NUMBER, $match[0], $reader->getPosition()));
+        $reader->moveForward(\strlen($match[0]));
+
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/StringHandler.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/StringHandler.php
new file mode 100644
index 0000000..ddaea64
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/StringHandler.php
@@ -0,0 +1,71 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\InternalErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\SyntaxErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerEscaping;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\TokenizerPatterns;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector comment handler.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class StringHandler implements HandlerInterface
+{
+    public function __construct(
+        private TokenizerPatterns $patterns,
+        private TokenizerEscaping $escaping,
+    ) {
+    }
+
+    public function handle(Reader $reader, TokenStream $stream): bool
+    {
+        $quote = $reader->getSubstring(1);
+
+        if (!\in_array($quote, ["'", '"'])) {
+            return false;
+        }
+
+        $reader->moveForward(1);
+        $match = $reader->findPattern($this->patterns->getQuotedStringPattern($quote));
+
+        if (!$match) {
+            throw new InternalErrorException(\sprintf('Should have found at least an empty match at %d.', $reader->getPosition()));
+        }
+
+        // check unclosed strings
+        if (\strlen($match[0]) === $reader->getRemainingLength()) {
+            throw SyntaxErrorException::unclosedString($reader->getPosition() - 1);
+        }
+
+        // check quotes pairs validity
+        if ($quote !== $reader->getSubstring(1, \strlen($match[0]))) {
+            throw SyntaxErrorException::unclosedString($reader->getPosition() - 1);
+        }
+
+        $string = $this->escaping->escapeUnicodeAndNewLine($match[0]);
+        $stream->push(new Token(Token::TYPE_STRING, $string, $reader->getPosition()));
+        $reader->moveForward(\strlen($match[0]) + 1);
+
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/WhitespaceHandler.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/WhitespaceHandler.php
new file mode 100644
index 0000000..d391ae2
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Handler/WhitespaceHandler.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector whitespace handler.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class WhitespaceHandler implements HandlerInterface
+{
+    public function handle(Reader $reader, TokenStream $stream): bool
+    {
+        $match = $reader->findPattern('~^[ \t\r\n\f]+~');
+
+        if (false === $match) {
+            return false;
+        }
+
+        $stream->push(new Token(Token::TYPE_WHITESPACE, $match[0], $reader->getPosition()));
+        $reader->moveForward(\strlen($match[0]));
+
+        return true;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Parser.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Parser.php
new file mode 100644
index 0000000..dc387bc
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Parser.php
@@ -0,0 +1,385 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\SyntaxErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer\Tokenizer;
+
+/**
+ * CSS selector parser.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/scrapy/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class Parser implements ParserInterface
+{
+    private Tokenizer $tokenizer;
+
+    public function __construct(?Tokenizer $tokenizer = null)
+    {
+        $this->tokenizer = $tokenizer ?? new Tokenizer();
+    }
+
+    public function parse(string $source): array
+    {
+        $reader = new Reader($source);
+        $stream = $this->tokenizer->tokenize($reader);
+
+        return $this->parseSelectorList($stream);
+    }
+
+    /**
+     * Parses the arguments for ":nth-child()" and friends.
+     *
+     * @param Token[] $tokens
+     *
+     * @throws SyntaxErrorException
+     */
+    public static function parseSeries(array $tokens): array
+    {
+        foreach ($tokens as $token) {
+            if ($token->isString()) {
+                throw SyntaxErrorException::stringAsFunctionArgument();
+            }
+        }
+
+        $joined = trim(implode('', array_map(fn (Token $token) => $token->getValue(), $tokens)));
+
+        $int = function ($string) {
+            if (!is_numeric($string)) {
+                throw SyntaxErrorException::stringAsFunctionArgument();
+            }
+
+            return (int) $string;
+        };
+
+        switch (true) {
+            case 'odd' === $joined:
+                return [2, 1];
+            case 'even' === $joined:
+                return [2, 0];
+            case 'n' === $joined:
+                return [1, 0];
+            case !str_contains($joined, 'n'):
+                return [0, $int($joined)];
+        }
+
+        $split = explode('n', $joined);
+        $first = $split[0] ?? null;
+
+        return [
+            $first ? ('-' === $first || '+' === $first ? $int($first.'1') : $int($first)) : 1,
+            isset($split[1]) && $split[1] ? $int($split[1]) : 0,
+        ];
+    }
+
+    private function parseSelectorList(TokenStream $stream, bool $isArgument = false): array
+    {
+        $stream->skipWhitespace();
+        $selectors = [];
+
+        while (true) {
+            if ($isArgument && $stream->getPeek()->isDelimiter([')'])) {
+                break;
+            }
+
+            $selectors[] = $this->parserSelectorNode($stream, $isArgument);
+
+            if ($stream->getPeek()->isDelimiter([','])) {
+                $stream->getNext();
+                $stream->skipWhitespace();
+            } else {
+                break;
+            }
+        }
+
+        return $selectors;
+    }
+
+    private function parserSelectorNode(TokenStream $stream, bool $isArgument = false): Node\SelectorNode
+    {
+        [$result, $pseudoElement] = $this->parseSimpleSelector($stream, false, $isArgument);
+
+        while (true) {
+            $stream->skipWhitespace();
+            $peek = $stream->getPeek();
+
+            if (
+                $peek->isFileEnd()
+                || $peek->isDelimiter([','])
+                || ($isArgument && $peek->isDelimiter([')']))
+            ) {
+                break;
+            }
+
+            if (null !== $pseudoElement) {
+                throw SyntaxErrorException::pseudoElementFound($pseudoElement, 'not at the end of a selector');
+            }
+
+            if ($peek->isDelimiter(['+', '>', '~'])) {
+                $combinator = $stream->getNext()->getValue();
+                $stream->skipWhitespace();
+            } else {
+                $combinator = ' ';
+            }
+
+            [$nextSelector, $pseudoElement] = $this->parseSimpleSelector($stream, false, $isArgument);
+            $result = new Node\CombinedSelectorNode($result, $combinator, $nextSelector);
+        }
+
+        return new Node\SelectorNode($result, $pseudoElement);
+    }
+
+    /**
+     * Parses next simple node (hash, class, pseudo, negation).
+     *
+     * @throws SyntaxErrorException
+     */
+    private function parseSimpleSelector(TokenStream $stream, bool $insideNegation = false, bool $isArgument = false): array
+    {
+        $stream->skipWhitespace();
+
+        $selectorStart = \count($stream->getUsed());
+        $result = $this->parseElementNode($stream);
+        $pseudoElement = null;
+
+        while (true) {
+            $peek = $stream->getPeek();
+            if ($peek->isWhitespace()
+                || $peek->isFileEnd()
+                || $peek->isDelimiter([',', '+', '>', '~'])
+                || ($isArgument && $peek->isDelimiter([')']))
+            ) {
+                break;
+            }
+
+            if (null !== $pseudoElement) {
+                throw SyntaxErrorException::pseudoElementFound($pseudoElement, 'not at the end of a selector');
+            }
+
+            if ($peek->isHash()) {
+                $result = new Node\HashNode($result, $stream->getNext()->getValue());
+            } elseif ($peek->isDelimiter(['.'])) {
+                $stream->getNext();
+                $result = new Node\ClassNode($result, $stream->getNextIdentifier());
+            } elseif ($peek->isDelimiter(['['])) {
+                $stream->getNext();
+                $result = $this->parseAttributeNode($result, $stream);
+            } elseif ($peek->isDelimiter([':'])) {
+                $stream->getNext();
+
+                if ($stream->getPeek()->isDelimiter([':'])) {
+                    $stream->getNext();
+                    $pseudoElement = $stream->getNextIdentifier();
+
+                    continue;
+                }
+
+                $identifier = $stream->getNextIdentifier();
+                if (\in_array(strtolower($identifier), ['first-line', 'first-letter', 'before', 'after'])) {
+                    // Special case: CSS 2.1 pseudo-elements can have a single ':'.
+                    // Any new pseudo-element must have two.
+                    $pseudoElement = $identifier;
+
+                    continue;
+                }
+
+                if (!$stream->getPeek()->isDelimiter(['('])) {
+                    $result = new Node\PseudoNode($result, $identifier);
+                    if ('Pseudo[Element[*]:scope]' === $result->__toString()) {
+                        $used = \count($stream->getUsed());
+                        if (!(2 === $used
+                           || 3 === $used && $stream->getUsed()[0]->isWhiteSpace()
+                           || $used >= 3 && $stream->getUsed()[$used - 3]->isDelimiter([','])
+                           || $used >= 4
+                                && $stream->getUsed()[$used - 3]->isWhiteSpace()
+                                && $stream->getUsed()[$used - 4]->isDelimiter([','])
+                        )) {
+                            throw SyntaxErrorException::notAtTheStartOfASelector('scope');
+                        }
+                    }
+                    continue;
+                }
+
+                $stream->getNext();
+                $stream->skipWhitespace();
+
+                if ('not' === strtolower($identifier)) {
+                    if ($insideNegation) {
+                        throw SyntaxErrorException::nestedNot();
+                    }
+
+                    [$argument, $argumentPseudoElement] = $this->parseSimpleSelector($stream, true, true);
+                    $next = $stream->getNext();
+
+                    if (null !== $argumentPseudoElement) {
+                        throw SyntaxErrorException::pseudoElementFound($argumentPseudoElement, 'inside ::not()');
+                    }
+
+                    if (!$next->isDelimiter([')'])) {
+                        throw SyntaxErrorException::unexpectedToken('")"', $next);
+                    }
+
+                    $result = new Node\NegationNode($result, $argument);
+                } elseif ('is' === strtolower($identifier)) {
+                    $selectors = $this->parseSelectorList($stream, true);
+
+                    $next = $stream->getNext();
+                    if (!$next->isDelimiter([')'])) {
+                        throw SyntaxErrorException::unexpectedToken('")"', $next);
+                    }
+
+                    $result = new Node\MatchingNode($result, $selectors);
+                } elseif ('where' === strtolower($identifier)) {
+                    $selectors = $this->parseSelectorList($stream, true);
+
+                    $next = $stream->getNext();
+                    if (!$next->isDelimiter([')'])) {
+                        throw SyntaxErrorException::unexpectedToken('")"', $next);
+                    }
+
+                    $result = new Node\SpecificityAdjustmentNode($result, $selectors);
+                } else {
+                    $arguments = [];
+                    $next = null;
+
+                    while (true) {
+                        $stream->skipWhitespace();
+                        $next = $stream->getNext();
+
+                        if ($next->isIdentifier()
+                            || $next->isString()
+                            || $next->isNumber()
+                            || $next->isDelimiter(['+', '-'])
+                        ) {
+                            $arguments[] = $next;
+                        } elseif ($next->isDelimiter([')'])) {
+                            break;
+                        } else {
+                            throw SyntaxErrorException::unexpectedToken('an argument', $next);
+                        }
+                    }
+
+                    if (!$arguments) {
+                        throw SyntaxErrorException::unexpectedToken('at least one argument', $next);
+                    }
+
+                    $result = new Node\FunctionNode($result, $identifier, $arguments);
+                }
+            } else {
+                throw SyntaxErrorException::unexpectedToken('selector', $peek);
+            }
+        }
+
+        if (\count($stream->getUsed()) === $selectorStart) {
+            throw SyntaxErrorException::unexpectedToken('selector', $stream->getPeek());
+        }
+
+        return [$result, $pseudoElement];
+    }
+
+    private function parseElementNode(TokenStream $stream): Node\ElementNode
+    {
+        $peek = $stream->getPeek();
+
+        if ($peek->isIdentifier() || $peek->isDelimiter(['*'])) {
+            if ($peek->isIdentifier()) {
+                $namespace = $stream->getNext()->getValue();
+            } else {
+                $stream->getNext();
+                $namespace = null;
+            }
+
+            if ($stream->getPeek()->isDelimiter(['|'])) {
+                $stream->getNext();
+                $element = $stream->getNextIdentifierOrStar();
+            } else {
+                $element = $namespace;
+                $namespace = null;
+            }
+        } else {
+            $element = $namespace = null;
+        }
+
+        return new Node\ElementNode($namespace, $element);
+    }
+
+    private function parseAttributeNode(Node\NodeInterface $selector, TokenStream $stream): Node\AttributeNode
+    {
+        $stream->skipWhitespace();
+        $attribute = $stream->getNextIdentifierOrStar();
+
+        if (null === $attribute && !$stream->getPeek()->isDelimiter(['|'])) {
+            throw SyntaxErrorException::unexpectedToken('"|"', $stream->getPeek());
+        }
+
+        if ($stream->getPeek()->isDelimiter(['|'])) {
+            $stream->getNext();
+
+            if ($stream->getPeek()->isDelimiter(['='])) {
+                $namespace = null;
+                $stream->getNext();
+                $operator = '|=';
+            } else {
+                $namespace = $attribute;
+                $attribute = $stream->getNextIdentifier();
+                $operator = null;
+            }
+        } else {
+            $namespace = $operator = null;
+        }
+
+        if (null === $operator) {
+            $stream->skipWhitespace();
+            $next = $stream->getNext();
+
+            if ($next->isDelimiter([']'])) {
+                return new Node\AttributeNode($selector, $namespace, $attribute, 'exists', null);
+            } elseif ($next->isDelimiter(['='])) {
+                $operator = '=';
+            } elseif ($next->isDelimiter(['^', '$', '*', '~', '|', '!'])
+                && $stream->getPeek()->isDelimiter(['='])
+            ) {
+                $operator = $next->getValue().'=';
+                $stream->getNext();
+            } else {
+                throw SyntaxErrorException::unexpectedToken('operator', $next);
+            }
+        }
+
+        $stream->skipWhitespace();
+        $value = $stream->getNext();
+
+        if ($value->isNumber()) {
+            // if the value is a number, it's casted into a string
+            $value = new Token(Token::TYPE_STRING, (string) $value->getValue(), $value->getPosition());
+        }
+
+        if (!($value->isIdentifier() || $value->isString())) {
+            throw SyntaxErrorException::unexpectedToken('string or identifier', $value);
+        }
+
+        $stream->skipWhitespace();
+        $next = $stream->getNext();
+
+        if (!$next->isDelimiter([']'])) {
+            throw SyntaxErrorException::unexpectedToken('"]"', $next);
+        }
+
+        return new Node\AttributeNode($selector, $namespace, $attribute, $operator, $value->getValue());
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/ParserInterface.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/ParserInterface.php
new file mode 100644
index 0000000..c1fe779
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/ParserInterface.php
@@ -0,0 +1,34 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+
+/**
+ * CSS selector parser interface.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+interface ParserInterface
+{
+    /**
+     * Parses given selector source into an array of tokens.
+     *
+     * @return SelectorNode[]
+     */
+    public function parse(string $source): array;
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Reader.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Reader.php
new file mode 100644
index 0000000..a3fd9bd
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Reader.php
@@ -0,0 +1,82 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser;
+
+/**
+ * CSS selector reader.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class Reader
+{
+    private int $length;
+    private int $position = 0;
+
+    public function __construct(
+        private string $source,
+    ) {
+        $this->length = \strlen($source);
+    }
+
+    public function isEOF(): bool
+    {
+        return $this->position >= $this->length;
+    }
+
+    public function getPosition(): int
+    {
+        return $this->position;
+    }
+
+    public function getRemainingLength(): int
+    {
+        return $this->length - $this->position;
+    }
+
+    public function getSubstring(int $length, int $offset = 0): string
+    {
+        return substr($this->source, $this->position + $offset, $length);
+    }
+
+    public function getOffset(string $string): int|false
+    {
+        $position = strpos($this->source, $string, $this->position);
+
+        return false === $position ? false : $position - $this->position;
+    }
+
+    public function findPattern(string $pattern): array|false
+    {
+        $source = substr($this->source, $this->position);
+
+        if (preg_match($pattern, $source, $matches)) {
+            return $matches;
+        }
+
+        return false;
+    }
+
+    public function moveForward(int $length): void
+    {
+        $this->position += $length;
+    }
+
+    public function moveToEnd(): void
+    {
+        $this->position = $this->length;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ClassParser.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ClassParser.php
new file mode 100644
index 0000000..e4614b2
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ClassParser.php
@@ -0,0 +1,48 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\ClassNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\ElementNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\ParserInterface;
+
+/**
+ * CSS selector class parser shortcut.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class ClassParser implements ParserInterface
+{
+    public function parse(string $source): array
+    {
+        // Matches an optional namespace, optional element, and required class
+        // $source = 'test|input.ab6bd_field';
+        // $matches = array (size=4)
+        //     0 => string 'test|input.ab6bd_field' (length=22)
+        //     1 => string 'test' (length=4)
+        //     2 => string 'input' (length=5)
+        //     3 => string 'ab6bd_field' (length=11)
+        if (preg_match('/^(?:([a-z]++)\|)?+([\w-]++|\*)?+\.([\w-]++)$/i', trim($source), $matches)) {
+            return [
+                new SelectorNode(new ClassNode(new ElementNode($matches[1] ?: null, $matches[2] ?: null), $matches[3])),
+            ];
+        }
+
+        return [];
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ElementParser.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ElementParser.php
new file mode 100644
index 0000000..7d4ad51
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/ElementParser.php
@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\ElementNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\ParserInterface;
+
+/**
+ * CSS selector element parser shortcut.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class ElementParser implements ParserInterface
+{
+    public function parse(string $source): array
+    {
+        // Matches an optional namespace, required element or `*`
+        // $source = 'testns|testel';
+        // $matches = array (size=3)
+        //     0 => string 'testns|testel' (length=13)
+        //     1 => string 'testns' (length=6)
+        //     2 => string 'testel' (length=6)
+        if (preg_match('/^(?:([a-z]++)\|)?([\w-]++|\*)$/i', trim($source), $matches)) {
+            return [new SelectorNode(new ElementNode($matches[1] ?: null, $matches[2]))];
+        }
+
+        return [];
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/EmptyStringParser.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/EmptyStringParser.php
new file mode 100644
index 0000000..3b4988c
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/EmptyStringParser.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\ElementNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\ParserInterface;
+
+/**
+ * CSS selector class parser shortcut.
+ *
+ * This shortcut ensure compatibility with previous version.
+ * - The parser fails to parse an empty string.
+ * - In the previous version, an empty string matches each tags.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class EmptyStringParser implements ParserInterface
+{
+    public function parse(string $source): array
+    {
+        // Matches an empty string
+        if ('' == $source) {
+            return [new SelectorNode(new ElementNode(null, '*'))];
+        }
+
+        return [];
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/HashParser.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/HashParser.php
new file mode 100644
index 0000000..b2c0bbe
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Shortcut/HashParser.php
@@ -0,0 +1,48 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Shortcut;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\ElementNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\HashNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\ParserInterface;
+
+/**
+ * CSS selector hash parser shortcut.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class HashParser implements ParserInterface
+{
+    public function parse(string $source): array
+    {
+        // Matches an optional namespace, optional element, and required id
+        // $source = 'test|input#ab6bd_field';
+        // $matches = array (size=4)
+        //     0 => string 'test|input#ab6bd_field' (length=22)
+        //     1 => string 'test' (length=4)
+        //     2 => string 'input' (length=5)
+        //     3 => string 'ab6bd_field' (length=11)
+        if (preg_match('/^(?:([a-z]++)\|)?+([\w-]++|\*)?+#([\w-]++)$/i', trim($source), $matches)) {
+            return [
+                new SelectorNode(new HashNode(new ElementNode($matches[1] ?: null, $matches[2] ?: null), $matches[3])),
+            ];
+        }
+
+        return [];
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Token.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Token.php
new file mode 100644
index 0000000..2855d4e
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Token.php
@@ -0,0 +1,107 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser;
+
+/**
+ * CSS selector token.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class Token
+{
+    public const TYPE_FILE_END = 'eof';
+    public const TYPE_DELIMITER = 'delimiter';
+    public const TYPE_WHITESPACE = 'whitespace';
+    public const TYPE_IDENTIFIER = 'identifier';
+    public const TYPE_HASH = 'hash';
+    public const TYPE_NUMBER = 'number';
+    public const TYPE_STRING = 'string';
+
+    public function __construct(
+        private ?string $type,
+        private ?string $value,
+        private ?int $position,
+    ) {
+    }
+
+    public function getType(): ?int
+    {
+        return $this->type;
+    }
+
+    public function getValue(): ?string
+    {
+        return $this->value;
+    }
+
+    public function getPosition(): ?int
+    {
+        return $this->position;
+    }
+
+    public function isFileEnd(): bool
+    {
+        return self::TYPE_FILE_END === $this->type;
+    }
+
+    public function isDelimiter(array $values = []): bool
+    {
+        if (self::TYPE_DELIMITER !== $this->type) {
+            return false;
+        }
+
+        if (!$values) {
+            return true;
+        }
+
+        return \in_array($this->value, $values, true);
+    }
+
+    public function isWhitespace(): bool
+    {
+        return self::TYPE_WHITESPACE === $this->type;
+    }
+
+    public function isIdentifier(): bool
+    {
+        return self::TYPE_IDENTIFIER === $this->type;
+    }
+
+    public function isHash(): bool
+    {
+        return self::TYPE_HASH === $this->type;
+    }
+
+    public function isNumber(): bool
+    {
+        return self::TYPE_NUMBER === $this->type;
+    }
+
+    public function isString(): bool
+    {
+        return self::TYPE_STRING === $this->type;
+    }
+
+    public function __toString(): string
+    {
+        if ($this->value) {
+            return \sprintf('<%s "%s" at %s>', $this->type, $this->value, $this->position);
+        }
+
+        return \sprintf('<%s at %s>', $this->type, $this->position);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/TokenStream.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/TokenStream.php
new file mode 100644
index 0000000..18361e2
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/TokenStream.php
@@ -0,0 +1,156 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\InternalErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\SyntaxErrorException;
+
+/**
+ * CSS selector token stream.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class TokenStream
+{
+    /**
+     * @var Token[]
+     */
+    private array $tokens = [];
+
+    /**
+     * @var Token[]
+     */
+    private array $used = [];
+
+    private int $cursor = 0;
+    private ?Token $peeked;
+    private bool $peeking = false;
+
+    /**
+     * Pushes a token.
+     *
+     * @return $this
+     */
+    public function push(Token $token): static
+    {
+        $this->tokens[] = $token;
+
+        return $this;
+    }
+
+    /**
+     * Freezes stream.
+     *
+     * @return $this
+     */
+    public function freeze(): static
+    {
+        return $this;
+    }
+
+    /**
+     * Returns next token.
+     *
+     * @throws InternalErrorException If there is no more token
+     */
+    public function getNext(): Token
+    {
+        if ($this->peeking) {
+            $this->peeking = false;
+            $this->used[] = $this->peeked;
+
+            return $this->peeked;
+        }
+
+        if (!isset($this->tokens[$this->cursor])) {
+            throw new InternalErrorException('Unexpected token stream end.');
+        }
+
+        return $this->tokens[$this->cursor++];
+    }
+
+    /**
+     * Returns peeked token.
+     */
+    public function getPeek(): Token
+    {
+        if (!$this->peeking) {
+            $this->peeked = $this->getNext();
+            $this->peeking = true;
+        }
+
+        return $this->peeked;
+    }
+
+    /**
+     * Returns used tokens.
+     *
+     * @return Token[]
+     */
+    public function getUsed(): array
+    {
+        return $this->used;
+    }
+
+    /**
+     * Returns next identifier token.
+     *
+     * @throws SyntaxErrorException If next token is not an identifier
+     */
+    public function getNextIdentifier(): string
+    {
+        $next = $this->getNext();
+
+        if (!$next->isIdentifier()) {
+            throw SyntaxErrorException::unexpectedToken('identifier', $next);
+        }
+
+        return $next->getValue();
+    }
+
+    /**
+     * Returns next identifier or null if star delimiter token is found.
+     *
+     * @throws SyntaxErrorException If next token is not an identifier or a star delimiter
+     */
+    public function getNextIdentifierOrStar(): ?string
+    {
+        $next = $this->getNext();
+
+        if ($next->isIdentifier()) {
+            return $next->getValue();
+        }
+
+        if ($next->isDelimiter(['*'])) {
+            return null;
+        }
+
+        throw SyntaxErrorException::unexpectedToken('identifier or "*"', $next);
+    }
+
+    /**
+     * Skips next whitespace if any.
+     */
+    public function skipWhitespace(): void
+    {
+        $peek = $this->getPeek();
+
+        if ($peek->isWhitespace()) {
+            $this->getNext();
+        }
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/Tokenizer.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/Tokenizer.php
new file mode 100644
index 0000000..6b39490
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/Tokenizer.php
@@ -0,0 +1,73 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Handler;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Reader;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Token;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\TokenStream;
+
+/**
+ * CSS selector tokenizer.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class Tokenizer
+{
+    /**
+     * @var Handler\HandlerInterface[]
+     */
+    private array $handlers;
+
+    public function __construct()
+    {
+        $patterns = new TokenizerPatterns();
+        $escaping = new TokenizerEscaping($patterns);
+
+        $this->handlers = [
+            new Handler\WhitespaceHandler(),
+            new Handler\IdentifierHandler($patterns, $escaping),
+            new Handler\HashHandler($patterns, $escaping),
+            new Handler\StringHandler($patterns, $escaping),
+            new Handler\NumberHandler($patterns),
+            new Handler\CommentHandler(),
+        ];
+    }
+
+    /**
+     * Tokenize selector source code.
+     */
+    public function tokenize(Reader $reader): TokenStream
+    {
+        $stream = new TokenStream();
+
+        while (!$reader->isEOF()) {
+            foreach ($this->handlers as $handler) {
+                if ($handler->handle($reader, $stream)) {
+                    continue 2;
+                }
+            }
+
+            $stream->push(new Token(Token::TYPE_DELIMITER, $reader->getSubstring(1), $reader->getPosition()));
+            $reader->moveForward(1);
+        }
+
+        return $stream
+            ->push(new Token(Token::TYPE_FILE_END, null, $reader->getPosition()))
+            ->freeze();
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerEscaping.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerEscaping.php
new file mode 100644
index 0000000..e509396
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerEscaping.php
@@ -0,0 +1,63 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer;
+
+/**
+ * CSS selector tokenizer escaping applier.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class TokenizerEscaping
+{
+    public function __construct(
+        private TokenizerPatterns $patterns,
+    ) {
+    }
+
+    public function escapeUnicode(string $value): string
+    {
+        $value = $this->replaceUnicodeSequences($value);
+
+        return preg_replace($this->patterns->getSimpleEscapePattern(), '$1', $value);
+    }
+
+    public function escapeUnicodeAndNewLine(string $value): string
+    {
+        $value = preg_replace($this->patterns->getNewLineEscapePattern(), '', $value);
+
+        return $this->escapeUnicode($value);
+    }
+
+    private function replaceUnicodeSequences(string $value): string
+    {
+        return preg_replace_callback($this->patterns->getUnicodeEscapePattern(), function ($match) {
+            $c = hexdec($match[1]);
+
+            if (0x80 > $c %= 0x200000) {
+                return \chr($c);
+            }
+            if (0x800 > $c) {
+                return \chr(0xC0 | $c >> 6).\chr(0x80 | $c & 0x3F);
+            }
+            if (0x10000 > $c) {
+                return \chr(0xE0 | $c >> 12).\chr(0x80 | $c >> 6 & 0x3F).\chr(0x80 | $c & 0x3F);
+            }
+
+            return '';
+        }, $value);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerPatterns.php b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerPatterns.php
new file mode 100644
index 0000000..eecd183
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/Parser/Tokenizer/TokenizerPatterns.php
@@ -0,0 +1,89 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Tokenizer;
+
+/**
+ * CSS selector tokenizer patterns builder.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class TokenizerPatterns
+{
+    private string $unicodeEscapePattern;
+    private string $simpleEscapePattern;
+    private string $newLineEscapePattern;
+    private string $escapePattern;
+    private string $stringEscapePattern;
+    private string $nonAsciiPattern;
+    private string $nmCharPattern;
+    private string $nmStartPattern;
+    private string $identifierPattern;
+    private string $hashPattern;
+    private string $numberPattern;
+    private string $quotedStringPattern;
+
+    public function __construct()
+    {
+        $this->unicodeEscapePattern = '\\\\([0-9a-f]{1,6})(?:\r\n|[ \n\r\t\f])?';
+        $this->simpleEscapePattern = '\\\\(.)';
+        $this->newLineEscapePattern = '\\\\(?:\n|\r\n|\r|\f)';
+        $this->escapePattern = $this->unicodeEscapePattern.'|\\\\[^\n\r\f0-9a-f]';
+        $this->stringEscapePattern = $this->newLineEscapePattern.'|'.$this->escapePattern;
+        $this->nonAsciiPattern = '[^\x00-\x7F]';
+        $this->nmCharPattern = '[_a-z0-9-]|'.$this->escapePattern.'|'.$this->nonAsciiPattern;
+        $this->nmStartPattern = '[_a-z]|'.$this->escapePattern.'|'.$this->nonAsciiPattern;
+        $this->identifierPattern = '-?(?:'.$this->nmStartPattern.')(?:'.$this->nmCharPattern.')*';
+        $this->hashPattern = '#((?:'.$this->nmCharPattern.')+)';
+        $this->numberPattern = '[+-]?(?:[0-9]*\.[0-9]+|[0-9]+)';
+        $this->quotedStringPattern = '([^\n\r\f\\\\%s]|'.$this->stringEscapePattern.')*';
+    }
+
+    public function getNewLineEscapePattern(): string
+    {
+        return '~'.$this->newLineEscapePattern.'~';
+    }
+
+    public function getSimpleEscapePattern(): string
+    {
+        return '~'.$this->simpleEscapePattern.'~';
+    }
+
+    public function getUnicodeEscapePattern(): string
+    {
+        return '~'.$this->unicodeEscapePattern.'~i';
+    }
+
+    public function getIdentifierPattern(): string
+    {
+        return '~^'.$this->identifierPattern.'~i';
+    }
+
+    public function getHashPattern(): string
+    {
+        return '~^'.$this->hashPattern.'~i';
+    }
+
+    public function getNumberPattern(): string
+    {
+        return '~^'.$this->numberPattern.'~';
+    }
+
+    public function getQuotedStringPattern(string $quote): string
+    {
+        return '~^'.\sprintf($this->quotedStringPattern, $quote).'~i';
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/README.md b/includes/Dependencies/Symfony/Component/CssSelector/README.md
new file mode 100644
index 0000000..ede4a3a
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/README.md
@@ -0,0 +1,20 @@
+CssSelector Component
+=====================
+
+The CssSelector component converts CSS selectors to XPath expressions.
+
+Resources
+---------
+
+ * [Documentation](https://symfony.com/doc/current/components/css_selector.html)
+ * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+ * [Report issues](https://github.com/symfony/symfony/issues) and
+   [send Pull Requests](https://github.com/symfony/symfony/pulls)
+   in the [main Symfony repository](https://github.com/symfony/symfony)
+
+Credits
+-------
+
+This component is a port of the Python cssselect library
+[v0.7.1](https://github.com/SimonSapin/cssselect/releases/tag/v0.7.1),
+which is distributed under the BSD license.
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AbstractExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AbstractExtension.php
new file mode 100644
index 0000000..542c81c
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AbstractExtension.php
@@ -0,0 +1,50 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+/**
+ * XPath expression translator abstract extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+abstract class AbstractExtension implements ExtensionInterface
+{
+    public function getNodeTranslators(): array
+    {
+        return [];
+    }
+
+    public function getCombinationTranslators(): array
+    {
+        return [];
+    }
+
+    public function getFunctionTranslators(): array
+    {
+        return [];
+    }
+
+    public function getPseudoClassTranslators(): array
+    {
+        return [];
+    }
+
+    public function getAttributeMatchingTranslators(): array
+    {
+        return [];
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AttributeMatchingExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AttributeMatchingExtension.php
new file mode 100644
index 0000000..919e6ba
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/AttributeMatchingExtension.php
@@ -0,0 +1,113 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Translator;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\XPathExpr;
+
+/**
+ * XPath expression translator attribute extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class AttributeMatchingExtension extends AbstractExtension
+{
+    public function getAttributeMatchingTranslators(): array
+    {
+        return [
+            'exists' => $this->translateExists(...),
+            '=' => $this->translateEquals(...),
+            '~=' => $this->translateIncludes(...),
+            '|=' => $this->translateDashMatch(...),
+            '^=' => $this->translatePrefixMatch(...),
+            '$=' => $this->translateSuffixMatch(...),
+            '*=' => $this->translateSubstringMatch(...),
+            '!=' => $this->translateDifferent(...),
+        ];
+    }
+
+    public function translateExists(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition($attribute);
+    }
+
+    public function translateEquals(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition(\sprintf('%s = %s', $attribute, Translator::getXpathLiteral($value)));
+    }
+
+    public function translateIncludes(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition($value ? \sprintf(
+            '%1$s and contains(concat(\' \', normalize-space(%1$s), \' \'), %2$s)',
+            $attribute,
+            Translator::getXpathLiteral(' '.$value.' ')
+        ) : '0');
+    }
+
+    public function translateDashMatch(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition(\sprintf(
+            '%1$s and (%1$s = %2$s or starts-with(%1$s, %3$s))',
+            $attribute,
+            Translator::getXpathLiteral($value),
+            Translator::getXpathLiteral($value.'-')
+        ));
+    }
+
+    public function translatePrefixMatch(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition($value ? \sprintf(
+            '%1$s and starts-with(%1$s, %2$s)',
+            $attribute,
+            Translator::getXpathLiteral($value)
+        ) : '0');
+    }
+
+    public function translateSuffixMatch(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition($value ? \sprintf(
+            '%1$s and substring(%1$s, string-length(%1$s)-%2$s) = %3$s',
+            $attribute,
+            \strlen($value) - 1,
+            Translator::getXpathLiteral($value)
+        ) : '0');
+    }
+
+    public function translateSubstringMatch(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition($value ? \sprintf(
+            '%1$s and contains(%1$s, %2$s)',
+            $attribute,
+            Translator::getXpathLiteral($value)
+        ) : '0');
+    }
+
+    public function translateDifferent(XPathExpr $xpath, string $attribute, ?string $value): XPathExpr
+    {
+        return $xpath->addCondition(\sprintf(
+            $value ? 'not(%1$s) or %1$s != %2$s' : '%s != %s',
+            $attribute,
+            Translator::getXpathLiteral($value)
+        ));
+    }
+
+    public function getName(): string
+    {
+        return 'attribute-matching';
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/CombinationExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/CombinationExtension.php
new file mode 100644
index 0000000..59794a4
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/CombinationExtension.php
@@ -0,0 +1,65 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\XPathExpr;
+
+/**
+ * XPath expression translator combination extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class CombinationExtension extends AbstractExtension
+{
+    public function getCombinationTranslators(): array
+    {
+        return [
+            ' ' => $this->translateDescendant(...),
+            '>' => $this->translateChild(...),
+            '+' => $this->translateDirectAdjacent(...),
+            '~' => $this->translateIndirectAdjacent(...),
+        ];
+    }
+
+    public function translateDescendant(XPathExpr $xpath, XPathExpr $combinedXpath): XPathExpr
+    {
+        return $xpath->join('/descendant-or-self::*/', $combinedXpath);
+    }
+
+    public function translateChild(XPathExpr $xpath, XPathExpr $combinedXpath): XPathExpr
+    {
+        return $xpath->join('/', $combinedXpath);
+    }
+
+    public function translateDirectAdjacent(XPathExpr $xpath, XPathExpr $combinedXpath): XPathExpr
+    {
+        return $xpath
+            ->join('/following-sibling::', $combinedXpath)
+            ->addNameTest()
+            ->addCondition('position() = 1');
+    }
+
+    public function translateIndirectAdjacent(XPathExpr $xpath, XPathExpr $combinedXpath): XPathExpr
+    {
+        return $xpath->join('/following-sibling::', $combinedXpath);
+    }
+
+    public function getName(): string
+    {
+        return 'combination';
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/ExtensionInterface.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/ExtensionInterface.php
new file mode 100644
index 0000000..db543a6
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/ExtensionInterface.php
@@ -0,0 +1,67 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+/**
+ * XPath expression translator extension interface.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+interface ExtensionInterface
+{
+    /**
+     * Returns node translators.
+     *
+     * These callables will receive the node as first argument and the translator as second argument.
+     *
+     * @return callable[]
+     */
+    public function getNodeTranslators(): array;
+
+    /**
+     * Returns combination translators.
+     *
+     * @return callable[]
+     */
+    public function getCombinationTranslators(): array;
+
+    /**
+     * Returns function translators.
+     *
+     * @return callable[]
+     */
+    public function getFunctionTranslators(): array;
+
+    /**
+     * Returns pseudo-class translators.
+     *
+     * @return callable[]
+     */
+    public function getPseudoClassTranslators(): array;
+
+    /**
+     * Returns attribute operation translators.
+     *
+     * @return callable[]
+     */
+    public function getAttributeMatchingTranslators(): array;
+
+    /**
+     * Returns extension name.
+     */
+    public function getName(): string;
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/FunctionExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/FunctionExtension.php
new file mode 100644
index 0000000..b274723
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/FunctionExtension.php
@@ -0,0 +1,165 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\ExpressionErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\SyntaxErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\FunctionNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Parser;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Translator;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\XPathExpr;
+
+/**
+ * XPath expression translator function extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class FunctionExtension extends AbstractExtension
+{
+    public function getFunctionTranslators(): array
+    {
+        return [
+            'nth-child' => $this->translateNthChild(...),
+            'nth-last-child' => $this->translateNthLastChild(...),
+            'nth-of-type' => $this->translateNthOfType(...),
+            'nth-last-of-type' => $this->translateNthLastOfType(...),
+            'contains' => $this->translateContains(...),
+            'lang' => $this->translateLang(...),
+        ];
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateNthChild(XPathExpr $xpath, FunctionNode $function, bool $last = false, bool $addNameTest = true): XPathExpr
+    {
+        try {
+            [$a, $b] = Parser::parseSeries($function->getArguments());
+        } catch (SyntaxErrorException $e) {
+            throw new ExpressionErrorException(\sprintf('Invalid series: "%s".', implode('", "', $function->getArguments())), 0, $e);
+        }
+
+        $xpath->addStarPrefix();
+        if ($addNameTest) {
+            $xpath->addNameTest();
+        }
+
+        if (0 === $a) {
+            return $xpath->addCondition('position() = '.($last ? 'last() - '.($b - 1) : $b));
+        }
+
+        if ($a < 0) {
+            if ($b < 1) {
+                return $xpath->addCondition('false()');
+            }
+
+            $sign = '<=';
+        } else {
+            $sign = '>=';
+        }
+
+        $expr = 'position()';
+
+        if ($last) {
+            $expr = 'last() - '.$expr;
+            --$b;
+        }
+
+        if (0 !== $b) {
+            $expr .= ' - '.$b;
+        }
+
+        $conditions = [\sprintf('%s %s 0', $expr, $sign)];
+
+        if (1 !== $a && -1 !== $a) {
+            $conditions[] = \sprintf('(%s) mod %d = 0', $expr, $a);
+        }
+
+        return $xpath->addCondition(implode(' and ', $conditions));
+
+        // todo: handle an+b, odd, even
+        // an+b means every-a, plus b, e.g., 2n+1 means odd
+        // 0n+b means b
+        // n+0 means a=1, i.e., all elements
+        // an means every a elements, i.e., 2n means even
+        // -n means -1n
+        // -1n+6 means elements 6 and previous
+    }
+
+    public function translateNthLastChild(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        return $this->translateNthChild($xpath, $function, true);
+    }
+
+    public function translateNthOfType(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        return $this->translateNthChild($xpath, $function, false, false);
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateNthLastOfType(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        if ('*' === $xpath->getElement()) {
+            throw new ExpressionErrorException('"*:nth-of-type()" is not implemented.');
+        }
+
+        return $this->translateNthChild($xpath, $function, true, false);
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateContains(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        $arguments = $function->getArguments();
+        foreach ($arguments as $token) {
+            if (!($token->isString() || $token->isIdentifier())) {
+                throw new ExpressionErrorException('Expected a single string or identifier for :contains(), got '.implode(', ', $arguments));
+            }
+        }
+
+        return $xpath->addCondition(\sprintf(
+            'contains(string(.), %s)',
+            Translator::getXpathLiteral($arguments[0]->getValue())
+        ));
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateLang(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        $arguments = $function->getArguments();
+        foreach ($arguments as $token) {
+            if (!($token->isString() || $token->isIdentifier())) {
+                throw new ExpressionErrorException('Expected a single string or identifier for :lang(), got '.implode(', ', $arguments));
+            }
+        }
+
+        return $xpath->addCondition(\sprintf(
+            'lang(%s)',
+            Translator::getXpathLiteral($arguments[0]->getValue())
+        ));
+    }
+
+    public function getName(): string
+    {
+        return 'function';
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/HtmlExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/HtmlExtension.php
new file mode 100644
index 0000000..b9523ce
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/HtmlExtension.php
@@ -0,0 +1,178 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\ExpressionErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\FunctionNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Translator;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\XPathExpr;
+
+/**
+ * XPath expression translator HTML extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class HtmlExtension extends AbstractExtension
+{
+    public function __construct(Translator $translator)
+    {
+        $translator
+            ->getExtension('node')
+            ->setFlag(NodeExtension::ELEMENT_NAME_IN_LOWER_CASE, true)
+            ->setFlag(NodeExtension::ATTRIBUTE_NAME_IN_LOWER_CASE, true);
+    }
+
+    public function getPseudoClassTranslators(): array
+    {
+        return [
+            'checked' => $this->translateChecked(...),
+            'link' => $this->translateLink(...),
+            'disabled' => $this->translateDisabled(...),
+            'enabled' => $this->translateEnabled(...),
+            'selected' => $this->translateSelected(...),
+            'invalid' => $this->translateInvalid(...),
+            'hover' => $this->translateHover(...),
+            'visited' => $this->translateVisited(...),
+        ];
+    }
+
+    public function getFunctionTranslators(): array
+    {
+        return [
+            'lang' => $this->translateLang(...),
+        ];
+    }
+
+    public function translateChecked(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition(
+            '(@checked '
+            ."and (name(.) = 'input' or name(.) = 'command')"
+            ."and (@type = 'checkbox' or @type = 'radio'))"
+        );
+    }
+
+    public function translateLink(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition("@href and (name(.) = 'a' or name(.) = 'link' or name(.) = 'area')");
+    }
+
+    public function translateDisabled(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition(
+            '('
+                .'@disabled and'
+                .'('
+                    ."(name(.) = 'input' and @type != 'hidden')"
+                    ." or name(.) = 'button'"
+                    ." or name(.) = 'select'"
+                    ." or name(.) = 'textarea'"
+                    ." or name(.) = 'command'"
+                    ." or name(.) = 'fieldset'"
+                    ." or name(.) = 'optgroup'"
+                    ." or name(.) = 'option'"
+                .')'
+            .') or ('
+                ."(name(.) = 'input' and @type != 'hidden')"
+                ." or name(.) = 'button'"
+                ." or name(.) = 'select'"
+                ." or name(.) = 'textarea'"
+            .')'
+            .' and ancestor::fieldset[@disabled]'
+        );
+        // todo: in the second half, add "and is not a descendant of that fieldset element's first legend element child, if any."
+    }
+
+    public function translateEnabled(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition(
+            '('
+                .'@href and ('
+                    ."name(.) = 'a'"
+                    ." or name(.) = 'link'"
+                    ." or name(.) = 'area'"
+                .')'
+            .') or ('
+                .'('
+                    ."name(.) = 'command'"
+                    ." or name(.) = 'fieldset'"
+                    ." or name(.) = 'optgroup'"
+                .')'
+                .' and not(@disabled)'
+            .') or ('
+                .'('
+                    ."(name(.) = 'input' and @type != 'hidden')"
+                    ." or name(.) = 'button'"
+                    ." or name(.) = 'select'"
+                    ." or name(.) = 'textarea'"
+                    ." or name(.) = 'keygen'"
+                .')'
+                .' and not (@disabled or ancestor::fieldset[@disabled])'
+            .') or ('
+                ."name(.) = 'option' and not("
+                    .'@disabled or ancestor::optgroup[@disabled]'
+                .')'
+            .')'
+        );
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateLang(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        $arguments = $function->getArguments();
+        foreach ($arguments as $token) {
+            if (!($token->isString() || $token->isIdentifier())) {
+                throw new ExpressionErrorException('Expected a single string or identifier for :lang(), got '.implode(', ', $arguments));
+            }
+        }
+
+        return $xpath->addCondition(\sprintf(
+            'ancestor-or-self::*[@lang][1][starts-with(concat('
+            ."translate(@%s, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'), '-')"
+            .', %s)]',
+            'lang',
+            Translator::getXpathLiteral(strtolower($arguments[0]->getValue()).'-')
+        ));
+    }
+
+    public function translateSelected(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition("(@selected and name(.) = 'option')");
+    }
+
+    public function translateInvalid(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition('0');
+    }
+
+    public function translateHover(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition('0');
+    }
+
+    public function translateVisited(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition('0');
+    }
+
+    public function getName(): string
+    {
+        return 'html';
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/NodeExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/NodeExtension.php
new file mode 100644
index 0000000..3845d9b
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/NodeExtension.php
@@ -0,0 +1,221 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Translator;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\XPathExpr;
+
+/**
+ * XPath expression translator node extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class NodeExtension extends AbstractExtension
+{
+    public const ELEMENT_NAME_IN_LOWER_CASE = 1;
+    public const ATTRIBUTE_NAME_IN_LOWER_CASE = 2;
+    public const ATTRIBUTE_VALUE_IN_LOWER_CASE = 4;
+
+    public function __construct(
+        private int $flags = 0,
+    ) {
+    }
+
+    /**
+     * @return $this
+     */
+    public function setFlag(int $flag, bool $on): static
+    {
+        if ($on && !$this->hasFlag($flag)) {
+            $this->flags += $flag;
+        }
+
+        if (!$on && $this->hasFlag($flag)) {
+            $this->flags -= $flag;
+        }
+
+        return $this;
+    }
+
+    public function hasFlag(int $flag): bool
+    {
+        return (bool) ($this->flags & $flag);
+    }
+
+    public function getNodeTranslators(): array
+    {
+        return [
+            'Selector' => $this->translateSelector(...),
+            'CombinedSelector' => $this->translateCombinedSelector(...),
+            'Negation' => $this->translateNegation(...),
+            'Matching' => $this->translateMatching(...),
+            'SpecificityAdjustment' => $this->translateSpecificityAdjustment(...),
+            'Function' => $this->translateFunction(...),
+            'Pseudo' => $this->translatePseudo(...),
+            'Attribute' => $this->translateAttribute(...),
+            'Class' => $this->translateClass(...),
+            'Hash' => $this->translateHash(...),
+            'Element' => $this->translateElement(...),
+        ];
+    }
+
+    public function translateSelector(Node\SelectorNode $node, Translator $translator): XPathExpr
+    {
+        return $translator->nodeToXPath($node->getTree());
+    }
+
+    public function translateCombinedSelector(Node\CombinedSelectorNode $node, Translator $translator): XPathExpr
+    {
+        return $translator->addCombination($node->getCombinator(), $node->getSelector(), $node->getSubSelector());
+    }
+
+    public function translateNegation(Node\NegationNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->getSelector());
+        $subXpath = $translator->nodeToXPath($node->getSubSelector());
+        $subXpath->addNameTest();
+
+        if ($subXpath->getCondition()) {
+            return $xpath->addCondition(\sprintf('not(%s)', $subXpath->getCondition()));
+        }
+
+        return $xpath->addCondition('0');
+    }
+
+    public function translateMatching(Node\MatchingNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->selector);
+
+        foreach ($node->arguments as $argument) {
+            $expr = $translator->nodeToXPath($argument);
+            $expr->addNameTest();
+            if ($condition = $expr->getCondition()) {
+                $xpath->addCondition($condition, 'or');
+            }
+        }
+
+        return $xpath;
+    }
+
+    public function translateSpecificityAdjustment(Node\SpecificityAdjustmentNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->selector);
+
+        foreach ($node->arguments as $argument) {
+            $expr = $translator->nodeToXPath($argument);
+            $expr->addNameTest();
+            if ($condition = $expr->getCondition()) {
+                $xpath->addCondition($condition, 'or');
+            }
+        }
+
+        return $xpath;
+    }
+
+    public function translateFunction(Node\FunctionNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->getSelector());
+
+        return $translator->addFunction($xpath, $node);
+    }
+
+    public function translatePseudo(Node\PseudoNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->getSelector());
+
+        return $translator->addPseudoClass($xpath, $node->getIdentifier());
+    }
+
+    public function translateAttribute(Node\AttributeNode $node, Translator $translator): XPathExpr
+    {
+        $name = $node->getAttribute();
+        $safe = $this->isSafeName($name);
+
+        if ($this->hasFlag(self::ATTRIBUTE_NAME_IN_LOWER_CASE)) {
+            $name = strtolower($name);
+        }
+
+        if ($node->getNamespace()) {
+            $name = \sprintf('%s:%s', $node->getNamespace(), $name);
+            $safe = $safe && $this->isSafeName($node->getNamespace());
+        }
+
+        $attribute = $safe ? '@'.$name : \sprintf('attribute::*[name() = %s]', Translator::getXpathLiteral($name));
+        $value = $node->getValue();
+        $xpath = $translator->nodeToXPath($node->getSelector());
+
+        if ($this->hasFlag(self::ATTRIBUTE_VALUE_IN_LOWER_CASE)) {
+            $value = strtolower($value);
+        }
+
+        return $translator->addAttributeMatching($xpath, $node->getOperator(), $attribute, $value);
+    }
+
+    public function translateClass(Node\ClassNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->getSelector());
+
+        return $translator->addAttributeMatching($xpath, '~=', '@class', $node->getName());
+    }
+
+    public function translateHash(Node\HashNode $node, Translator $translator): XPathExpr
+    {
+        $xpath = $translator->nodeToXPath($node->getSelector());
+
+        return $translator->addAttributeMatching($xpath, '=', '@id', $node->getId());
+    }
+
+    public function translateElement(Node\ElementNode $node): XPathExpr
+    {
+        $element = $node->getElement();
+
+        if ($element && $this->hasFlag(self::ELEMENT_NAME_IN_LOWER_CASE)) {
+            $element = strtolower($element);
+        }
+
+        if ($element) {
+            $safe = $this->isSafeName($element);
+        } else {
+            $element = '*';
+            $safe = true;
+        }
+
+        if ($node->getNamespace()) {
+            $element = \sprintf('%s:%s', $node->getNamespace(), $element);
+            $safe = $safe && $this->isSafeName($node->getNamespace());
+        }
+
+        $xpath = new XPathExpr('', $element);
+
+        if (!$safe) {
+            $xpath->addNameTest();
+        }
+
+        return $xpath;
+    }
+
+    public function getName(): string
+    {
+        return 'node';
+    }
+
+    private function isSafeName(string $name): bool
+    {
+        return 0 < preg_match('~^[a-zA-Z_][a-zA-Z0-9_.-]*$~', $name);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/PseudoClassExtension.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/PseudoClassExtension.php
new file mode 100644
index 0000000..dc5ad3b
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Extension/PseudoClassExtension.php
@@ -0,0 +1,122 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\Extension;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\ExpressionErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath\XPathExpr;
+
+/**
+ * XPath expression translator pseudo-class extension.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class PseudoClassExtension extends AbstractExtension
+{
+    public function getPseudoClassTranslators(): array
+    {
+        return [
+            'root' => $this->translateRoot(...),
+            'scope' => $this->translateScopePseudo(...),
+            'first-child' => $this->translateFirstChild(...),
+            'last-child' => $this->translateLastChild(...),
+            'first-of-type' => $this->translateFirstOfType(...),
+            'last-of-type' => $this->translateLastOfType(...),
+            'only-child' => $this->translateOnlyChild(...),
+            'only-of-type' => $this->translateOnlyOfType(...),
+            'empty' => $this->translateEmpty(...),
+        ];
+    }
+
+    public function translateRoot(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition('not(parent::*)');
+    }
+
+    public function translateScopePseudo(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition('1');
+    }
+
+    public function translateFirstChild(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath
+            ->addStarPrefix()
+            ->addNameTest()
+            ->addCondition('position() = 1');
+    }
+
+    public function translateLastChild(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath
+            ->addStarPrefix()
+            ->addNameTest()
+            ->addCondition('position() = last()');
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateFirstOfType(XPathExpr $xpath): XPathExpr
+    {
+        if ('*' === $xpath->getElement()) {
+            throw new ExpressionErrorException('"*:first-of-type" is not implemented.');
+        }
+
+        return $xpath
+            ->addStarPrefix()
+            ->addCondition('position() = 1');
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function translateLastOfType(XPathExpr $xpath): XPathExpr
+    {
+        if ('*' === $xpath->getElement()) {
+            throw new ExpressionErrorException('"*:last-of-type" is not implemented.');
+        }
+
+        return $xpath
+            ->addStarPrefix()
+            ->addCondition('position() = last()');
+    }
+
+    public function translateOnlyChild(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath
+            ->addStarPrefix()
+            ->addNameTest()
+            ->addCondition('last() = 1');
+    }
+
+    public function translateOnlyOfType(XPathExpr $xpath): XPathExpr
+    {
+        $element = $xpath->getElement();
+
+        return $xpath->addCondition(\sprintf('count(preceding-sibling::%s)=0 and count(following-sibling::%s)=0', $element, $element));
+    }
+
+    public function translateEmpty(XPathExpr $xpath): XPathExpr
+    {
+        return $xpath->addCondition('not(*) and not(string-length())');
+    }
+
+    public function getName(): string
+    {
+        return 'pseudo-class';
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/Translator.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Translator.php
new file mode 100644
index 0000000..ab85a26
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/Translator.php
@@ -0,0 +1,224 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Exception\ExpressionErrorException;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\FunctionNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\NodeInterface;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\Parser;
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Parser\ParserInterface;
+
+/**
+ * XPath expression translator interface.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class Translator implements TranslatorInterface
+{
+    private ParserInterface $mainParser;
+
+    /**
+     * @var ParserInterface[]
+     */
+    private array $shortcutParsers = [];
+
+    /**
+     * @var Extension\ExtensionInterface[]
+     */
+    private array $extensions = [];
+
+    private array $nodeTranslators = [];
+    private array $combinationTranslators = [];
+    private array $functionTranslators = [];
+    private array $pseudoClassTranslators = [];
+    private array $attributeMatchingTranslators = [];
+
+    public function __construct(?ParserInterface $parser = null)
+    {
+        $this->mainParser = $parser ?? new Parser();
+
+        $this
+            ->registerExtension(new Extension\NodeExtension())
+            ->registerExtension(new Extension\CombinationExtension())
+            ->registerExtension(new Extension\FunctionExtension())
+            ->registerExtension(new Extension\PseudoClassExtension())
+            ->registerExtension(new Extension\AttributeMatchingExtension())
+        ;
+    }
+
+    public static function getXpathLiteral(string $element): string
+    {
+        if (!str_contains($element, "'")) {
+            return "'".$element."'";
+        }
+
+        if (!str_contains($element, '"')) {
+            return '"'.$element.'"';
+        }
+
+        $string = $element;
+        $parts = [];
+        while (true) {
+            if (false !== $pos = strpos($string, "'")) {
+                $parts[] = \sprintf("'%s'", substr($string, 0, $pos));
+                $parts[] = "\"'\"";
+                $string = substr($string, $pos + 1);
+            } else {
+                $parts[] = "'$string'";
+                break;
+            }
+        }
+
+        return \sprintf('concat(%s)', implode(', ', $parts));
+    }
+
+    public function cssToXPath(string $cssExpr, string $prefix = 'descendant-or-self::'): string
+    {
+        $selectors = $this->parseSelectors($cssExpr);
+
+        /** @var SelectorNode $selector */
+        foreach ($selectors as $index => $selector) {
+            if (null !== $selector->getPseudoElement()) {
+                throw new ExpressionErrorException('Pseudo-elements are not supported.');
+            }
+
+            $selectors[$index] = $this->selectorToXPath($selector, $prefix);
+        }
+
+        return implode(' | ', $selectors);
+    }
+
+    public function selectorToXPath(SelectorNode $selector, string $prefix = 'descendant-or-self::'): string
+    {
+        return ($prefix ?: '').$this->nodeToXPath($selector);
+    }
+
+    /**
+     * @return $this
+     */
+    public function registerExtension(Extension\ExtensionInterface $extension): static
+    {
+        $this->extensions[$extension->getName()] = $extension;
+
+        $this->nodeTranslators = array_merge($this->nodeTranslators, $extension->getNodeTranslators());
+        $this->combinationTranslators = array_merge($this->combinationTranslators, $extension->getCombinationTranslators());
+        $this->functionTranslators = array_merge($this->functionTranslators, $extension->getFunctionTranslators());
+        $this->pseudoClassTranslators = array_merge($this->pseudoClassTranslators, $extension->getPseudoClassTranslators());
+        $this->attributeMatchingTranslators = array_merge($this->attributeMatchingTranslators, $extension->getAttributeMatchingTranslators());
+
+        return $this;
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function getExtension(string $name): Extension\ExtensionInterface
+    {
+        if (!isset($this->extensions[$name])) {
+            throw new ExpressionErrorException(\sprintf('Extension "%s" not registered.', $name));
+        }
+
+        return $this->extensions[$name];
+    }
+
+    /**
+     * @return $this
+     */
+    public function registerParserShortcut(ParserInterface $shortcut): static
+    {
+        $this->shortcutParsers[] = $shortcut;
+
+        return $this;
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function nodeToXPath(NodeInterface $node): XPathExpr
+    {
+        if (!isset($this->nodeTranslators[$node->getNodeName()])) {
+            throw new ExpressionErrorException(\sprintf('Node "%s" not supported.', $node->getNodeName()));
+        }
+
+        return $this->nodeTranslators[$node->getNodeName()]($node, $this);
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function addCombination(string $combiner, NodeInterface $xpath, NodeInterface $combinedXpath): XPathExpr
+    {
+        if (!isset($this->combinationTranslators[$combiner])) {
+            throw new ExpressionErrorException(\sprintf('Combiner "%s" not supported.', $combiner));
+        }
+
+        return $this->combinationTranslators[$combiner]($this->nodeToXPath($xpath), $this->nodeToXPath($combinedXpath));
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function addFunction(XPathExpr $xpath, FunctionNode $function): XPathExpr
+    {
+        if (!isset($this->functionTranslators[$function->getName()])) {
+            throw new ExpressionErrorException(\sprintf('Function "%s" not supported.', $function->getName()));
+        }
+
+        return $this->functionTranslators[$function->getName()]($xpath, $function);
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function addPseudoClass(XPathExpr $xpath, string $pseudoClass): XPathExpr
+    {
+        if (!isset($this->pseudoClassTranslators[$pseudoClass])) {
+            throw new ExpressionErrorException(\sprintf('Pseudo-class "%s" not supported.', $pseudoClass));
+        }
+
+        return $this->pseudoClassTranslators[$pseudoClass]($xpath);
+    }
+
+    /**
+     * @throws ExpressionErrorException
+     */
+    public function addAttributeMatching(XPathExpr $xpath, string $operator, string $attribute, ?string $value): XPathExpr
+    {
+        if (!isset($this->attributeMatchingTranslators[$operator])) {
+            throw new ExpressionErrorException(\sprintf('Attribute matcher operator "%s" not supported.', $operator));
+        }
+
+        return $this->attributeMatchingTranslators[$operator]($xpath, $attribute, $value);
+    }
+
+    /**
+     * @return SelectorNode[]
+     */
+    private function parseSelectors(string $css): array
+    {
+        foreach ($this->shortcutParsers as $shortcut) {
+            $tokens = $shortcut->parse($css);
+
+            if ($tokens) {
+                return $tokens;
+            }
+        }
+
+        return $this->mainParser->parse($css);
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/TranslatorInterface.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/TranslatorInterface.php
new file mode 100644
index 0000000..a7fe223
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/TranslatorInterface.php
@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath;
+
+use Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\Node\SelectorNode;
+
+/**
+ * XPath expression translator interface.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+interface TranslatorInterface
+{
+    /**
+     * Translates a CSS selector to an XPath expression.
+     */
+    public function cssToXPath(string $cssExpr, string $prefix = 'descendant-or-self::'): string;
+
+    /**
+     * Translates a parsed selector node to an XPath expression.
+     */
+    public function selectorToXPath(SelectorNode $selector, string $prefix = 'descendant-or-self::'): string;
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/XPath/XPathExpr.php b/includes/Dependencies/Symfony/Component/CssSelector/XPath/XPathExpr.php
new file mode 100644
index 0000000..6d314b4
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/XPath/XPathExpr.php
@@ -0,0 +1,107 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eighteen73\Orbit\Dependencies\Symfony\Component\CssSelector\XPath;
+
+/**
+ * XPath expression translator interface.
+ *
+ * This component is a port of the Python cssselect library,
+ * which is copyright Ian Bicking, @see https://github.com/SimonSapin/cssselect.
+ *
+ * @author Jean-François Simon <jeanfrancois.simon@sensiolabs.com>
+ *
+ * @internal
+ */
+class XPathExpr
+{
+    public function __construct(
+        private string $path = '',
+        private string $element = '*',
+        private string $condition = '',
+        bool $starPrefix = false,
+    ) {
+        if ($starPrefix) {
+            $this->addStarPrefix();
+        }
+    }
+
+    public function getElement(): string
+    {
+        return $this->element;
+    }
+
+    /**
+     * @return $this
+     */
+    public function addCondition(string $condition, string $operator = 'and'): static
+    {
+        $this->condition = $this->condition ? \sprintf('(%s) %s (%s)', $this->condition, $operator, $condition) : $condition;
+
+        return $this;
+    }
+
+    public function getCondition(): string
+    {
+        return $this->condition;
+    }
+
+    /**
+     * @return $this
+     */
+    public function addNameTest(): static
+    {
+        if ('*' !== $this->element) {
+            $this->addCondition('name() = '.Translator::getXpathLiteral($this->element));
+            $this->element = '*';
+        }
+
+        return $this;
+    }
+
+    /**
+     * @return $this
+     */
+    public function addStarPrefix(): static
+    {
+        $this->path .= '*/';
+
+        return $this;
+    }
+
+    /**
+     * Joins another XPathExpr with a combiner.
+     *
+     * @return $this
+     */
+    public function join(string $combiner, self $expr): static
+    {
+        $path = $this->__toString().$combiner;
+
+        if ('*/' !== $expr->path) {
+            $path .= $expr->path;
+        }
+
+        $this->path = $path;
+        $this->element = $expr->element;
+        $this->condition = $expr->condition;
+
+        return $this;
+    }
+
+    public function __toString(): string
+    {
+        $path = $this->path.$this->element;
+        $condition = '' === $this->condition ? '' : '['.$this->condition.']';
+
+        return $path.$condition;
+    }
+}
diff --git a/includes/Dependencies/Symfony/Component/CssSelector/composer.json b/includes/Dependencies/Symfony/Component/CssSelector/composer.json
new file mode 100644
index 0000000..a753a1a
--- /dev/null
+++ b/includes/Dependencies/Symfony/Component/CssSelector/composer.json
@@ -0,0 +1,32 @@
+{
+    "name": "symfony/css-selector",
+    "type": "library",
+    "description": "Converts CSS selectors to XPath expressions",
+    "keywords": [],
+    "homepage": "https://symfony.com",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Fabien Potencier",
+            "email": "fabien@symfony.com"
+        },
+        {
+            "name": "Jean-François Simon",
+            "email": "jeanfrancois.simon@sensiolabs.com"
+        },
+        {
+            "name": "Symfony Community",
+            "homepage": "https://symfony.com/contributors"
+        }
+    ],
+    "require": {
+        "php": ">=8.2"
+    },
+    "autoload": {
+        "psr-4": { "Symfony\\Component\\CssSelector\\": "" },
+        "exclude-from-classmap": [
+            "/Tests/"
+        ]
+    },
+    "minimum-stability": "dev"
+}
diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 12c7e18..0b67f27 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -8,7 +8,8 @@
 namespace Eighteen73\Orbit;
 
 use Exception;
-use Pelago\Emogrifier\CssInliner;
+use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\CssInliner;
+
 /**
  * This class is built upon BE Media from Production so all due credit to those authors.
  * http://www.github.com/billerickson/be-media-from-production
diff --git a/orbit.php b/orbit.php
index 9033fcb..0dbcbea 100644
--- a/orbit.php
+++ b/orbit.php
@@ -25,7 +25,6 @@
 define( 'ORBIT_PATH', plugin_dir_path( __FILE__ ) );
 define( 'ORBIT_INC', ORBIT_PATH . 'includes/' );
 
-require_once ORBIT_PATH . '/vendor/autoload.php';
 require_once 'autoload.php';
 
 DisallowIndexing\DisallowIndexing::instance()->setup();

From b7f30084acdf7576d11a70d155a88a49365f0247 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Thu, 7 Aug 2025 13:44:18 +0100
Subject: [PATCH 11/25] New: ignore dependencies folder in code sniffer

---
 phpcs.xml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/phpcs.xml b/phpcs.xml
index 9abac53..2211dc9 100644
--- a/phpcs.xml
+++ b/phpcs.xml
@@ -5,6 +5,7 @@
 	<!-- Scan all files in directory -->
 	<file>.</file>
 	<exclude-pattern type="relative">lib/packages/*</exclude-pattern>
+	<exclude-pattern type="relative">includes/Dependencies/*</exclude-pattern>
 
 	<!-- Scan only PHP files -->
 	<arg name="extensions" value="php"/>

From 54dcc64092b6aa88f226402a9697ab036357f9c0 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Thu, 7 Aug 2025 15:23:47 +0100
Subject: [PATCH 12/25] Fix: remove left margin from logo

---
 templates/branded-emails/email-styles.php | 1 -
 1 file changed, 1 deletion(-)

diff --git a/templates/branded-emails/email-styles.php b/templates/branded-emails/email-styles.php
index a9356bc..e88756a 100644
--- a/templates/branded-emails/email-styles.php
+++ b/templates/branded-emails/email-styles.php
@@ -196,7 +196,6 @@
 		text-decoration: none;
 		text-transform: capitalize;
 		vertical-align: middle;
-		margin-left: 24px;
 		max-width: 100%;
 	}
 

From 3c23e8b55778817c7f3f91f9bcd6acf52859c63f Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Thu, 7 Aug 2025 16:13:37 +0100
Subject: [PATCH 13/25] Fix: resolve setting values that aren't hexcodes

---
 includes/classes/BrandedEmails.php        | 108 ++++++++++++++++++++++
 templates/branded-emails/email-styles.php |  66 ++++++-------
 2 files changed, 138 insertions(+), 36 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 0b67f27..4d77d0f 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -139,4 +139,112 @@ public function style_inline( $email_content ) {
 
 		return $inlined_content;
 	}
+
+	/**
+	 * Retrieves a set of resolved and filtered CSS variables used for branded email templates.
+	 *
+	 * @return array Array of CSS variables for use in the email template.
+	 */
+	public static function get_css_variables() {
+		$global_settings = wp_get_global_settings();
+
+		return [
+			'background_color' => apply_filters(
+				'orbit_branded_emails_background_color',
+				'#ffffff'
+			),
+
+			'body_background_color' => apply_filters(
+				'orbit_branded_emails_body_background_color',
+				'#ffffff'
+			),
+
+			'body_border_color' => apply_filters(
+				'orbit_branded_emails_body_border_color',
+				self::orbit_branded_emails_resolve_color(
+					$global_settings['custom']['color']['border'] ?? '',
+					'#EDEFF1'
+				)
+			),
+
+			'body_text_color' => apply_filters(
+				'orbit_branded_emails_body_text_color',
+				self::orbit_branded_emails_resolve_color(
+					$global_settings['color']['contrast'] ?? '',
+					'#3F474D'
+				)
+			),
+
+			'link_color' => apply_filters(
+				'orbit_branded_emails_link_color',
+				self::orbit_branded_emails_resolve_color(
+					$global_settings['custom']['color']['link'] ?? '',
+					'#8549FF'
+				)
+			),
+
+			'footer_text_color' => apply_filters(
+				'orbit_branded_emails_footer_text_color',
+				self::orbit_branded_emails_resolve_color(
+					$global_settings['color']['contrast'] ?? '',
+					'#3F474D'
+				)
+			),
+
+			'font_family' => '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif',
+
+			'logo_image_width' => apply_filters( 'orbit_branded_emails_logo_image_width', 200 ),
+		];
+	}
+
+	/**
+	 * Resolves a color value from a theme.json setting to a usable HEX color string.
+	 *
+	 * This function accepts a color value which may be a direct HEX code or a CSS variable
+	 * (e.g. `var(--wp--preset--color--primary)` or `var(--wp--custom--color--custom-blue)`),
+	 * and attempts to resolve it to a valid HEX color by looking up the appropriate values
+	 * in the provided theme.json structure.
+	 *
+	 * It supports recursive resolution in case the referenced color is itself another variable.
+	 *
+	 * @param string $color_value The raw color value to resolve. Can be a HEX code or a CSS variable.
+	 * @param string $fallback Optional fallback value to return if resolution fails. Defaults to null.
+	 *
+	 * @return string|null The resolved HEX color code (e.g. "#ffffff"), or null if resolution fails.
+	 */
+	public static function orbit_branded_emails_resolve_color( $color_value, $fallback = null ) {
+		$theme_json = wp_get_global_settings();
+
+		// If it's already a hex code, just return it
+		if ( preg_match( '/^#(?:[0-9a-fA-F]{3}){1,2}$/', $color_value ) ) {
+			return $color_value;
+		}
+
+		// Match CSS variable format
+		if ( preg_match( '/var\(--wp--(preset|custom)--color--([a-zA-Z0-9_-]+)\)/', $color_value, $matches ) ) {
+			$type        = $matches[1]; // 'preset' or 'custom'
+			$color_slug  = $matches[2];
+
+			if ( $type === 'preset' ) {
+				$presets = $theme_json['settings']['color']['palette'] ?? [];
+
+				foreach ( $presets as $preset ) {
+					if ( $preset['slug'] === $color_slug ) {
+						return self::orbit_branded_emails_resolve_color( $preset['color'], $theme_json );
+					}
+				}
+			}
+
+			if ( $type === 'custom' ) {
+				$custom_colors = $theme_json['custom']['color'] ?? [];
+
+				if ( isset( $custom_colors[ $color_slug ] ) ) {
+					return self::orbit_branded_emails_resolve_color( $custom_colors[ $color_slug ], $theme_json );
+				}
+			}
+		}
+
+		// Return null if unable to resolve
+		return $fallback;
+	}
 }
diff --git a/templates/branded-emails/email-styles.php b/templates/branded-emails/email-styles.php
index e88756a..f98065a 100644
--- a/templates/branded-emails/email-styles.php
+++ b/templates/branded-emails/email-styles.php
@@ -6,35 +6,29 @@
  * @package         Orbit
  */
 
+namespace Eighteen73\Orbit;
+
 if ( ! defined( 'ABSPATH' ) ) {
 	exit; // Exit if accessed directly.
 }
 
-$global_settings = wp_get_global_settings();
-$background_color = apply_filters( 'orbit_branded_emails_background_color', '#ffffff' );
-$body_background_color = apply_filters( 'orbit_branded_emails_body_background_color', '#ffffff' );
-$body_border_color = apply_filters( 'orbit_branded_emails_body_border_color', $global_settings['custom']['color']['border'] ?? '#EDEFF1' );
-$body_text_color = apply_filters( 'orbit_branded_emails_body_text_color', $global_settings['color']['contrast'] ?? '#3F474D' );
-$link_color = apply_filters( 'orbit_branded_emails_link_color', $global_settings['custom']['color']['link'] ?? '#8549FF' );
-$footer_text_color = apply_filters( 'orbit_branded_emails_footer_text_color', $global_settings['color']['contrast'] ?? '#3F474D' );
-$font_family = '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif';
-$logo_image_width = apply_filters( 'orbit_branded_emails_logo_image_width', 200 );
+$css_variables = BrandedEmails::get_css_variables();
 ?>
 
 <style>
 	body {
-		background: <?php echo esc_attr( $background_color ); ?>;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		background: <?php echo esc_attr( $css_variables['background_color'] ); ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		padding: 0;
 		text-align: center;
 	}
 
 	#outer_wrapper {
-		background: <?php echo esc_attr( $background_color ); ?>;
+		background: <?php echo esc_attr( $css_variables['background_color'] ); ?>;
 	}
 
 	#inner_wrapper {
-		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+		background-color: <?php echo esc_attr( $css_variables['body_background_color'] ); ?>;
 		border-radius: 6px;
 	}
 
@@ -47,23 +41,23 @@
 	}
 
 	#template_container {
-		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+		background-color: <?php echo esc_attr( $css_variables['body_background_color'] ); ?>;
 		border-radius: 3px !important;
 	}
 
 	#template_header {
-		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+		background-color: <?php echo esc_attr( $css_variables['body_background_color'] ); ?>;
 		border-radius: 3px 3px 0 0 !important;
-		color: <?php echo esc_attr( $body_text_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
 		border-bottom: 0;
 		font-weight: bold;
 		line-height: 100%;
 		vertical-align: middle;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 	}
 
 	#template_header h1 {
-		color: <?php echo esc_attr( $body_text_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
 		background-color: inherit;
 	}
 
@@ -77,12 +71,12 @@
 	}
 
 	#template_header_image img {
-		width: <?php echo esc_attr( $logo_image_width ); ?>px;
+		width: <?php echo esc_attr( $css_variables['logo_image_width'] ); ?>px;
 	}
 
 	.email-logo-text {
-		color: <?php echo esc_attr( $link_color ); ?>;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		color: <?php echo esc_attr( $css_variables['link_color'] ); ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 18px;
 	}
 
@@ -96,9 +90,9 @@
 
 	#template_footer #credit {
 		border: 0;
-		border-top: 1px solid <?php echo esc_attr( $body_border_color ); ?>;
-		color: <?php echo esc_attr( $footer_text_color ); ?>;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		border-top: 1px solid <?php echo esc_attr( $css_variables['body_border_color'] ); ?>;
+		color: <?php echo esc_attr( $css_variables['footer_text_color'] ); ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 12px;
 		line-height: 140%;
 		text-align: center;
@@ -110,7 +104,7 @@
 	}
 
 	#body_content {
-		background-color: <?php echo esc_attr( $body_background_color ); ?>;
+		background-color: <?php echo esc_attr( $css_variables['body_background_color'] ); ?>;
 	}
 
 	#body_content table td th {
@@ -121,8 +115,8 @@
 	}
 
 	#body_content_inner {
-		color: <?php echo esc_attr( $body_text_color ); ?>;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 16px;
 		line-height: 150%;
 		text-align: left;
@@ -133,7 +127,7 @@
 	}
 
 	.td {
-		color: <?php echo esc_attr( $body_text_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
 		vertical-align: middle;
 	}
 
@@ -144,12 +138,12 @@
 
 	#template_footer #credit,
 	#template_footer #credit a {
-		color: <?php echo esc_attr( $footer_text_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['footer_text_color'] ); ?>;
 	}
 
 	h1 {
-		color: <?php echo esc_attr( $body_text_color ); ?>;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 32px;
 		font-weight: 700;
 		letter-spacing: -1px;
@@ -159,9 +153,9 @@
 	}
 
 	h2 {
-		color: <?php echo esc_attr( $body_text_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
 		display: block;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 20px;
 		font-weight: bold;
 		line-height: 160%;
@@ -170,9 +164,9 @@
 	}
 
 	h3 {
-		color: <?php echo esc_attr( $body_text_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['body_text_color'] ); ?>;
 		display: block;
-		font-family: <?php echo $font_family; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
+		font-family: <?php echo $css_variables['font_family']; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped ?>;
 		font-size: 16px;
 		font-weight: bold;
 		line-height: 160%;
@@ -181,7 +175,7 @@
 	}
 
 	a {
-		color: <?php echo esc_attr( $link_color ); ?>;
+		color: <?php echo esc_attr( $css_variables['link_color'] ); ?>;
 		font-weight: normal;
 		text-decoration: underline;
 	}

From 1fdf907592ea0f82647355896b0769f01c1d65e0 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Thu, 7 Aug 2025 16:46:29 +0100
Subject: [PATCH 14/25] New: use woocommerce colours if they are set

---
 includes/classes/BrandedEmails.php | 33 +++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 4d77d0f..378b1bd 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -151,11 +151,13 @@ public static function get_css_variables() {
 		return [
 			'background_color' => apply_filters(
 				'orbit_branded_emails_background_color',
+				get_option( 'woocommerce_email_background_color' ) ?:
 				'#ffffff'
 			),
 
 			'body_background_color' => apply_filters(
 				'orbit_branded_emails_body_background_color',
+				get_option( 'woocommerce_email_body_background_color' ) ?:
 				'#ffffff'
 			),
 
@@ -163,37 +165,44 @@ public static function get_css_variables() {
 				'orbit_branded_emails_body_border_color',
 				self::orbit_branded_emails_resolve_color(
 					$global_settings['custom']['color']['border'] ?? '',
-					'#EDEFF1'
-				)
+				) ?:
+				'#EDEFF1'
 			),
 
 			'body_text_color' => apply_filters(
 				'orbit_branded_emails_body_text_color',
+				get_option( 'woocommerce_email_text_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['color']['contrast'] ?? '',
-					'#3F474D'
-				)
+					$global_settings['color']['contrast'] ?? ''
+				) ?:
+				'#3F474D'
 			),
 
 			'link_color' => apply_filters(
 				'orbit_branded_emails_link_color',
+				get_option( 'woocommerce_email_base_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['custom']['color']['link'] ?? '',
-					'#8549FF'
-				)
+					$global_settings['custom']['color']['link'] ?? ''
+				) ?:
+				'#8549FF'
 			),
 
 			'footer_text_color' => apply_filters(
 				'orbit_branded_emails_footer_text_color',
+				get_option( 'woocommerce_email_footer_text_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['color']['contrast'] ?? '',
-					'#3F474D'
-				)
+					$global_settings['color']['contrast'] ?? ''
+				) ?:
+				'#3F474D'
 			),
 
 			'font_family' => '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif',
 
-			'logo_image_width' => apply_filters( 'orbit_branded_emails_logo_image_width', 200 ),
+			'logo_image_width' => apply_filters(
+				'orbit_branded_emails_logo_image_width',
+				get_option( 'woocommerce_email_header_image_width' ) ?:
+				120
+			),
 		];
 	}
 

From 09c14a212da5cde62d228a0021a1a294a4ff7a1c Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Fri, 8 Aug 2025 15:53:44 +0100
Subject: [PATCH 15/25] New: gravity forms branding in emails

---
 includes/classes/BrandedEmails.php | 32 ++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 378b1bd..7f46882 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -31,6 +31,8 @@ public function setup() {
 
 		add_filter( 'wp_mail', [ $this, 'apply_branded_email_template' ] );
 		add_filter( 'gform_html_message_template_pre_send_email', [ $this, 'apply_branded_email_template_to_gf_notifications' ] );
+		add_filter( 'gform_email_background_color_label', [ $this, 'apply_branded_email_colours_to_gf_table_labels' ], 10, 3 );
+		add_filter( 'gform_email_background_color_data', [ $this, 'apply_branded_email_colours_to_gf_table_data' ], 10, 3 );
 	}
 
 	/**
@@ -256,4 +258,34 @@ public static function orbit_branded_emails_resolve_color( $color_value, $fallba
 		// Return null if unable to resolve
 		return $fallback;
 	}
+
+	public static function apply_branded_email_colours_to_gf_table_labels( $color, $field, $lead ) {
+		$global_settings = wp_get_global_settings();
+
+		$tint_color = null;
+		$theme_palette = $global_settings['color']['palette']['theme'] ?? [];
+
+		foreach ( $theme_palette as $palette_item ) {
+			if ( isset( $palette_item['slug'] ) && $palette_item['slug'] === 'tint' ) {
+				$tint_color = self::orbit_branded_emails_resolve_color( $palette_item['color'] );
+				break;
+			}
+		}
+
+		$label_background_color = apply_filters(
+			'orbit_branded_emails_gf_label_bg_color',
+			$tint_color ?: $color
+		);
+
+		return $label_background_color ?: $color;
+	}
+
+	public static function apply_branded_email_colours_to_gf_table_data( $color, $field, $entry ) {
+		$data_background_color = apply_filters(
+			'orbit_branded_emails_gf_data_bg_color',
+			$color
+		);
+
+		return $data_background_color;
+	}
 }

From 61cecf573fffaef51462cdc32f8c635a8897df09 Mon Sep 17 00:00:00 2001
From: Brett Mason <brett@eighteen73.co.uk>
Date: Mon, 11 Aug 2025 08:56:42 +0100
Subject: [PATCH 16/25] Add method comments for phpcs

---
 includes/classes/BrandedEmails.php | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 7f46882..1e73f5a 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -259,6 +259,16 @@ public static function orbit_branded_emails_resolve_color( $color_value, $fallba
 		return $fallback;
 	}
 
+	/**
+	 * Applies branded email colours to Gravity Forms table labels.
+	 *
+	 * @see https://docs.gravityforms.com/gform_email_background_color_label/
+	 *
+	 * @param string        $color The current background color.
+	 * @param GF_Field_Name $field The current field.
+	 * @param array         $lead The current lead.
+	 * @return string The modified color value.
+	 */
 	public static function apply_branded_email_colours_to_gf_table_labels( $color, $field, $lead ) {
 		$global_settings = wp_get_global_settings();
 
@@ -280,6 +290,16 @@ public static function apply_branded_email_colours_to_gf_table_labels( $color, $
 		return $label_background_color ?: $color;
 	}
 
+	/**
+	 * Applies branded email colours to Gravity Forms table data.
+	 *
+	 * @see https://docs.gravityforms.com/gform_email_background_color_data/
+	 *
+	 * @param string        $color The current background color.
+	 * @param GF_Field_Name $field The current field.
+	 * @param array         $entry The current entry.
+	 * @return string The modified color value.
+	 */
 	public static function apply_branded_email_colours_to_gf_table_data( $color, $field, $entry ) {
 		$data_background_color = apply_filters(
 			'orbit_branded_emails_gf_data_bg_color',

From 6c84e95881ed2d7fe56123aff03e93526a97ab05 Mon Sep 17 00:00:00 2001
From: Brett Mason <brett@eighteen73.co.uk>
Date: Mon, 11 Aug 2025 08:59:47 +0100
Subject: [PATCH 17/25] Correct class comment

---
 includes/classes/BrandedEmails.php | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 1e73f5a..3bffca9 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -2,7 +2,7 @@
 /**
  * Add branding email templates to site emails.
  *
- * @package         Orbit
+ * @package Orbit
  */
 
 namespace Eighteen73\Orbit;
@@ -11,8 +11,7 @@
 use Eighteen73\Orbit\Dependencies\Pelago\Emogrifier\CssInliner;
 
 /**
- * This class is built upon BE Media from Production so all due credit to those authors.
- * http://www.github.com/billerickson/be-media-from-production
+ * Branded Emails class.
  */
 class BrandedEmails {
 

From 464a9155b3ce095f8acfc06108e391d3d60cbd11 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 10:02:40 +0100
Subject: [PATCH 18/25] New: update colour resolver to work with direct
 variable declarations and multi layer variables

---
 includes/classes/BrandedEmails.php | 80 +++++++++++++++++++-----------
 1 file changed, 50 insertions(+), 30 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 7f46882..65666f8 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -166,36 +166,36 @@ public static function get_css_variables() {
 			'body_border_color' => apply_filters(
 				'orbit_branded_emails_body_border_color',
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['custom']['color']['border'] ?? '',
+					'var(--wp--custom--color--border)'
 				) ?:
-				'#EDEFF1'
+				'#edeff1'
 			),
 
 			'body_text_color' => apply_filters(
 				'orbit_branded_emails_body_text_color',
 				get_option( 'woocommerce_email_text_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['color']['contrast'] ?? ''
+					'var(--wp--preset--color--contrast)'
 				) ?:
-				'#3F474D'
+				'#3f474d'
 			),
 
 			'link_color' => apply_filters(
 				'orbit_branded_emails_link_color',
 				get_option( 'woocommerce_email_base_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['custom']['color']['link'] ?? ''
+					'var(--wp--custom--color--link)'
 				) ?:
-				'#8549FF'
+				'#8549ff'
 			),
 
 			'footer_text_color' => apply_filters(
 				'orbit_branded_emails_footer_text_color',
 				get_option( 'woocommerce_email_footer_text_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
-					$global_settings['color']['contrast'] ?? ''
+					'var(--wp--preset--color--contrast)'
 				) ?:
-				'#3F474D'
+				'#3F474d'
 			),
 
 			'font_family' => '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif',
@@ -226,22 +226,22 @@ public static function get_css_variables() {
 	public static function orbit_branded_emails_resolve_color( $color_value, $fallback = null ) {
 		$theme_json = wp_get_global_settings();
 
-		// If it's already a hex code, just return it
+		// If already a hex code, just return it.
 		if ( preg_match( '/^#(?:[0-9a-fA-F]{3}){1,2}$/', $color_value ) ) {
 			return $color_value;
 		}
 
 		// Match CSS variable format
-		if ( preg_match( '/var\(--wp--(preset|custom)--color--([a-zA-Z0-9_-]+)\)/', $color_value, $matches ) ) {
-			$type        = $matches[1]; // 'preset' or 'custom'
-			$color_slug  = $matches[2];
+		if ( preg_match( '/var\(--wp--(preset|custom)--color--([a-zA-Z0-9_-]+(?:--[a-zA-Z0-9_-]+)*)\)/', $color_value, $matches ) ) {
+			$type       = $matches[1]; // 'preset' or 'custom'
+			$color_slug = $matches[2];
 
 			if ( $type === 'preset' ) {
-				$presets = $theme_json['settings']['color']['palette'] ?? [];
+				$presets = $theme_json['color']['palette']['theme'] ?? [];
 
 				foreach ( $presets as $preset ) {
 					if ( $preset['slug'] === $color_slug ) {
-						return self::orbit_branded_emails_resolve_color( $preset['color'], $theme_json );
+						return self::orbit_branded_emails_resolve_color( $preset['color'], $fallback );
 					}
 				}
 			}
@@ -249,37 +249,57 @@ public static function orbit_branded_emails_resolve_color( $color_value, $fallba
 			if ( $type === 'custom' ) {
 				$custom_colors = $theme_json['custom']['color'] ?? [];
 
-				if ( isset( $custom_colors[ $color_slug ] ) ) {
-					return self::orbit_branded_emails_resolve_color( $custom_colors[ $color_slug ], $theme_json );
+				$keys = explode( '--', $color_slug );
+
+				$value = $custom_colors;
+				foreach ( $keys as $key ) {
+					if ( isset( $value[ $key ] ) ) {
+						$value = $value[ $key ];
+					} else {
+						$value = null;
+						break;
+					}
+				}
+
+				if ( $value ) {
+					return self::orbit_branded_emails_resolve_color( $value, $fallback );
 				}
 			}
 		}
 
-		// Return null if unable to resolve
 		return $fallback;
 	}
 
+	/**
+	 * Applies branded email background colors to Gravity Forms table label cells.
+	 *
+	 * @param string $color The default background color for the table label cell.
+	 * @param array  $field The Gravity Forms field data for the current cell.
+	 * @param array  $lead The Gravity Forms entry data for the current form submission.
+	 *
+	 * @return string The resolved background color after applying the filter.
+	 */
 	public static function apply_branded_email_colours_to_gf_table_labels( $color, $field, $lead ) {
-		$global_settings = wp_get_global_settings();
-
-		$tint_color = null;
-		$theme_palette = $global_settings['color']['palette']['theme'] ?? [];
-
-		foreach ( $theme_palette as $palette_item ) {
-			if ( isset( $palette_item['slug'] ) && $palette_item['slug'] === 'tint' ) {
-				$tint_color = self::orbit_branded_emails_resolve_color( $palette_item['color'] );
-				break;
-			}
-		}
-
 		$label_background_color = apply_filters(
 			'orbit_branded_emails_gf_label_bg_color',
-			$tint_color ?: $color
+			self::orbit_branded_emails_resolve_color(
+				'var(--wp--preset--color--tint)'
+			) ?:
+			$color
 		);
 
 		return $label_background_color ?: $color;
 	}
 
+	/**
+	 * Applies branded email background colors to Gravity Forms table data cells.
+	 *
+	 * @param string $color The default background color for the table data cell.
+	 * @param array  $field The Gravity Forms field data for the current cell.
+	 * @param array  $entry The Gravity Forms entry data for the current form submission.
+	 *
+	 * @return string The resolved background color after applying the filter.
+	 */
 	public static function apply_branded_email_colours_to_gf_table_data( $color, $field, $entry ) {
 		$data_background_color = apply_filters(
 			'orbit_branded_emails_gf_data_bg_color',

From 10609b660c1eb829b97ffef1b98ea891010bf0d9 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 10:10:46 +0100
Subject: [PATCH 19/25] Tidy: remove unused variable

---
 includes/classes/BrandedEmails.php | 2 --
 1 file changed, 2 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 4b231bb..0496301 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -147,8 +147,6 @@ public function style_inline( $email_content ) {
 	 * @return array Array of CSS variables for use in the email template.
 	 */
 	public static function get_css_variables() {
-		$global_settings = wp_get_global_settings();
-
 		return [
 			'background_color' => apply_filters(
 				'orbit_branded_emails_background_color',

From e07a037bedd5705bd0a617d76e159bc642cff352 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 10:56:37 +0100
Subject: [PATCH 20/25] New: check if woocommerce is active before getting
 settings, hook for setting email font

---
 includes/classes/BrandedEmails.php | 35 ++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index 0496301..c609c9b 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -150,13 +150,13 @@ public static function get_css_variables() {
 		return [
 			'background_color' => apply_filters(
 				'orbit_branded_emails_background_color',
-				get_option( 'woocommerce_email_background_color' ) ?:
+				self::get_woocommerce_setting( 'woocommerce_email_background_color' ) ?:
 				'#ffffff'
 			),
 
 			'body_background_color' => apply_filters(
 				'orbit_branded_emails_body_background_color',
-				get_option( 'woocommerce_email_body_background_color' ) ?:
+				self::get_woocommerce_setting( 'woocommerce_email_body_background_color' ) ?:
 				'#ffffff'
 			),
 
@@ -170,7 +170,7 @@ public static function get_css_variables() {
 
 			'body_text_color' => apply_filters(
 				'orbit_branded_emails_body_text_color',
-				get_option( 'woocommerce_email_text_color' ) ?:
+				self::get_woocommerce_setting( 'woocommerce_email_text_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
 					'var(--wp--preset--color--contrast)'
 				) ?:
@@ -179,7 +179,7 @@ public static function get_css_variables() {
 
 			'link_color' => apply_filters(
 				'orbit_branded_emails_link_color',
-				get_option( 'woocommerce_email_base_color' ) ?:
+				self::get_woocommerce_setting( 'woocommerce_email_base_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
 					'var(--wp--custom--color--link)'
 				) ?:
@@ -188,18 +188,22 @@ public static function get_css_variables() {
 
 			'footer_text_color' => apply_filters(
 				'orbit_branded_emails_footer_text_color',
-				get_option( 'woocommerce_email_footer_text_color' ) ?:
+				self::get_woocommerce_setting( 'woocommerce_email_footer_text_color' ) ?:
 				self::orbit_branded_emails_resolve_color(
 					'var(--wp--preset--color--contrast)'
 				) ?:
 				'#3F474d'
 			),
 
-			'font_family' => '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif',
+			'font_family' => apply_filters(
+				'orbit_branded_emails_font_family',
+				self::get_woocommerce_setting( 'woocommerce_email_font_family' ) ?:
+				'"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif'
+			),
 
 			'logo_image_width' => apply_filters(
 				'orbit_branded_emails_logo_image_width',
-				get_option( 'woocommerce_email_header_image_width' ) ?:
+				self::get_woocommerce_setting( 'woocommerce_email_header_image_width' ) ?:
 				120
 			),
 		];
@@ -306,4 +310,21 @@ public static function apply_branded_email_colours_to_gf_table_data( $color, $fi
 
 		return $data_background_color;
 	}
+
+	/**
+	 * Checks if WooCommerce is active and retrieves a specific setting.
+	 *
+	 * Should only be used for settings that are expected to be set by WooCommerce.
+	 *
+	 * @param string $setting_name The name of the WooCommerce setting to retrieve.
+	 * @return mixed|null The value of the setting, or null if WooCommerce is not active or the setting does not exist.
+	 */
+	public static function get_woocommerce_setting( $setting_name ) {
+		// check if woocommerce is active
+		if ( ! class_exists( 'WooCommerce' ) ) {
+			return null;
+		}
+
+		return get_option( $setting_name ) ?: null;
+	}
 }

From 989c691f682c624cb3a6cbc7dc8f345718d2fb0b Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 11:06:26 +0100
Subject: [PATCH 21/25] New: rename filter for disabling branded emails

---
 includes/classes/BrandedEmails.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/includes/classes/BrandedEmails.php b/includes/classes/BrandedEmails.php
index c609c9b..d269745 100644
--- a/includes/classes/BrandedEmails.php
+++ b/includes/classes/BrandedEmails.php
@@ -24,7 +24,7 @@ class BrandedEmails {
 	 * @return void
 	 */
 	public function setup() {
-		if ( apply_filters( 'orbit_branded_emails_disable', false ) ) {
+		if ( ! apply_filters( 'orbit_enable_branded_emails', true ) ) {
 			return;
 		}
 

From a7ff01b1bf40386d55199cf91926638d2ac858c0 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 11:27:30 +0100
Subject: [PATCH 22/25] New: document branded emails feature

---
 README.md                                   | 20 ++++++++++++++++++++
 templates/branded-emails/email-styles.php   |  5 +++--
 templates/branded-emails/email-template.php |  5 ++---
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 10ed1d3..465ed63 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,13 @@ If necessary, you may install it manually by downloading a Zip archive from [Git
 
 ## Summary of Features
 
+### Branded Emails
+- Adds branding to emails that aren't set to be 'text/html'
+- Adds branding to Gravity Forms notification emails
+- When possible uses WooCommerce email branding for consistenty
+- Main email template can be overriden by copying `templates/branded-emails/email-template.php` into `yourtheme/orbit/branded-emails`
+- Email styles template can be overriden by copying `templates/branded-emails/email-styles.php` into `yourtheme/orbit/branded-emails`
+
 ### UI Cleanup
 
 - Remove unwanted items from the menu (with limited configuration)
@@ -71,6 +78,19 @@ The following filters can be used to override the default behavior of certain fe
 -   `orbit_enable_rest_api_user_endpoints`: Enable or disable REST API user endpoints. Default `false` (disabled).
 -   `orbit_remote_files_url`: Override the production URL used for loading remote media files. Default value comes from `ORBIT_REMOTE_FILES_URL`.
 
+### Branded Emails
+
+-   `orbit_enable_branded_emails`: Enable Orbit's branded emails feature. Default `true` (enabled).
+-   `orbit_branded_emails_header_logo`: Set the logo image in branded emails. Default `''` (empty).
+-   `orbit_branded_emails_background_color`: Set the background color of branded emails. Default `woocommerce_email_background_color || '#ffffff'`.
+-   `orbit_branded_emails_body_background_color`: Set the body background color of branded emails. Default `woocommerce_email_body_background_color || '#ffffff'`.
+-   `orbit_branded_emails_body_border_color`: Set the border color of branded emails. Default `var(--wp--custom--color--border) || '#edeff1'`.
+-   `orbit_branded_emails_body_text_color`: Set the body text color of branded emails. Default `woocommerce_email_text_color || var(--wp--preset--color--contrast) || '#3f474d'`.
+-   `orbit_branded_emails_link_color`: Set the link color color of branded emails. Default `woocommerce_email_base_color || var(--wp--custom--color--link) || '#8549ff'`.
+-   `orbit_branded_emails_footer_text_color`: Set the footer text color of branded emails. Default `woocommerce_email_footer_text_color || var(--wp--preset--color--contrast) || '#3F474d'`.
+-   `orbit_branded_emails_font_family`: Set the font family of branded emails. Default `woocommerce_email_font_family || '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif'`.
+-   `orbit_branded_emails_logo_image_width`: Set the logo image width in branded emails. Default `woocommerce_email_header_image_width || 120`.
+
 ### Examples
 
 You can use standard WordPress functions like `__return_true` and `__return_false` to easily toggle these features. Add the following lines to your theme or a custom plugin:
diff --git a/templates/branded-emails/email-styles.php b/templates/branded-emails/email-styles.php
index f98065a..bb21635 100644
--- a/templates/branded-emails/email-styles.php
+++ b/templates/branded-emails/email-styles.php
@@ -1,9 +1,10 @@
 <?php
 /**
  * Branded Email Styles
- * This file can be overridden in your theme.
  *
- * @package         Orbit
+ * This template can be overridden by copying it to yourtheme/orbit/branded-emails/email-styles.php.
+ *
+ * @package Orbit
  */
 
 namespace Eighteen73\Orbit;
diff --git a/templates/branded-emails/email-template.php b/templates/branded-emails/email-template.php
index b5daeb2..84bfde4 100644
--- a/templates/branded-emails/email-template.php
+++ b/templates/branded-emails/email-template.php
@@ -1,11 +1,10 @@
 <?php
 /**
  * Branded Email Template
- * This file can be overridden in your theme.
  *
- * @package         Orbit
+ * This template can be overridden by copying it to yourtheme/orbit/branded-emails/email-template.php.
  *
- * @var string $email_content
+ * @package Orbit
  */
 
 namespace Eighteen73\Orbit;

From 31ac628c88ead4052777d066d37a078dee8f53f4 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 11:30:40 +0100
Subject: [PATCH 23/25] New: additional documentation on branded emails

---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index 465ed63..4942727 100644
--- a/README.md
+++ b/README.md
@@ -80,6 +80,8 @@ The following filters can be used to override the default behavior of certain fe
 
 ### Branded Emails
 
+The following filters can be used to override default behaviour/values of branded email features.
+
 -   `orbit_enable_branded_emails`: Enable Orbit's branded emails feature. Default `true` (enabled).
 -   `orbit_branded_emails_header_logo`: Set the logo image in branded emails. Default `''` (empty).
 -   `orbit_branded_emails_background_color`: Set the background color of branded emails. Default `woocommerce_email_background_color || '#ffffff'`.

From da7cb394943d0f73bcc37f6908fbbed2bca73de8 Mon Sep 17 00:00:00 2001
From: Dan Hudson <dan@orphans.co.uk>
Date: Mon, 11 Aug 2025 11:43:16 +0100
Subject: [PATCH 24/25] New: categorise filters documentation

---
 README.md | 57 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 39 insertions(+), 18 deletions(-)

diff --git a/README.md b/README.md
index 4942727..766a7c8 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,7 @@ If necessary, you may install it manually by downloading a Zip archive from [Git
 - Remove unwanted dashboard widgets
 - Replace the login logo (configurable)
 - Remove the footer message in CMS
+- Adds an environment icon to indicate the configured environment type
 
 ### Security
 
@@ -60,24 +61,6 @@ If necessary, you may install it manually by downloading a Zip archive from [Git
 
 ## Available Filters
 
-The following filters can be used to override the default behavior of certain features. Set the filter to `true` to enable the feature, or `false` to disable it.
-
--   `orbit_enable_wordpress_updates`: Control the visibility of the WordPress updates item in the toolbar. Default `false` (hidden).
--   `orbit_enable_xmlrpc`: Enable or disable XML-RPC functionality. Default `false` (disabled).
--   `orbit_enable_user_caps_access`: Enable Orbit's user capability restrictions. Default `true` (enabled).
--   `orbit_enable_editor_caps_access`: Enable Orbit's editor capability restrictions. Default `true` (enabled).
--   `orbit_enable_gravity_forms_access`: Enable Orbit's Gravity Forms capability restrictions. Default `true` (enabled).
--   `orbit_enable_expose_wordpress_version`: Show or hide the WordPress version in the site's frontend markup. Default `false` (hidden).
--   `orbit_enable_admin_environment_name`: Control the display of the environment name in the admin area. Default `true` (enabled).
--   `orbit_enable_menu_item_dashboard`: Control the visibility of the Dashboard menu item. Default `true` (visible).
--   `orbit_enable_menu_item_posts`: Control the visibility of the Posts menu item. Default `true` (visible).
--   `orbit_enable_menu_item_comments`: Control the visibility of the Comments menu item and toolbar item. Default `false` (hidden).
--   `orbit_enable_toolbar_item_new_content`: Control the visibility of the "New Content" item in the toolbar. Default `true` (visible).
--   `orbit_enable_login_logo`: Enable replacement of the login logo. Default `true` (enabled).
--   `orbit_login_logo_url`: Provide a URL to replace the default WordPress login logo. No default.
--   `orbit_enable_rest_api_user_endpoints`: Enable or disable REST API user endpoints. Default `false` (disabled).
--   `orbit_remote_files_url`: Override the production URL used for loading remote media files. Default value comes from `ORBIT_REMOTE_FILES_URL`.
-
 ### Branded Emails
 
 The following filters can be used to override default behaviour/values of branded email features.
@@ -93,6 +76,44 @@ The following filters can be used to override default behaviour/values of brande
 -   `orbit_branded_emails_font_family`: Set the font family of branded emails. Default `woocommerce_email_font_family || '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif'`.
 -   `orbit_branded_emails_logo_image_width`: Set the logo image width in branded emails. Default `woocommerce_email_header_image_width || 120`.
 
+### UI Cleanup
+
+The following filters can be used to override the default behavior of certain features. Set the filter to `true` to enable the feature, or `false` to disable it.
+
+-   `orbit_enable_menu_item_dashboard`: Control the visibility of the Dashboard menu item. Default `true` (visible).
+-   `orbit_enable_menu_item_posts`: Control the visibility of the Posts menu item. Default `true` (visible).
+-   `orbit_enable_menu_item_comments`: Control the visibility of the Comments menu item and toolbar item. Default `false` (hidden).
+-   `orbit_enable_toolbar_item_new_content`: Control the visibility of the "New Content" item in the toolbar. Default `true` (visible).
+-   `orbit_enable_login_logo`: Enable replacement of the login logo. Default `true` (enabled).
+-   `orbit_login_logo_url`: Provide a URL to replace the default WordPress login logo. No default.
+-   `orbit_enable_admin_environment_name`: Control the display of the environment name in the admin area. Default `true` (enabled).
+
+### Security
+
+The following filters can be used to override the default behavior of certain features. Set the filter to `true` to enable the feature, or `false` to disable it.
+
+-   `orbit_enable_rest_api_user_endpoints`: Enable or disable REST API user endpoints. Default `false` (disabled).
+-   `orbit_enable_xmlrpc`: Enable or disable XML-RPC functionality. Default `false` (disabled).
+-   `orbit_enable_expose_wordpress_version`: Show or hide the WordPress version in the site's frontend markup. Default `false` (hidden).
+
+### Capabilities
+
+The following filters can be used to override the default behavior of certain features. Set the filter to `true` to enable the feature, or `false` to disable it.
+
+-   `orbit_enable_user_caps_access`: Enable Orbit's user capability restrictions. Default `true` (enabled).
+-   `orbit_enable_editor_caps_access`: Enable Orbit's editor capability restrictions. Default `true` (enabled).
+-   `orbit_enable_gravity_forms_access`: Enable Orbit's Gravity Forms capability restrictions. Default `true` (enabled).
+
+### Other Safety Measures
+
+The following filters can be used to override the default behavior of certain features. Set the filter to `true` to enable the feature, or `false` to disable it.
+
+-   `orbit_enable_wordpress_updates`: Control the visibility of the WordPress updates item in the toolbar. Default `false` (hidden).
+
+### Other Features
+
+-   `orbit_remote_files_url`: Override the production URL used for loading remote media files. Default value comes from `ORBIT_REMOTE_FILES_URL`.
+
 ### Examples
 
 You can use standard WordPress functions like `__return_true` and `__return_false` to easily toggle these features. Add the following lines to your theme or a custom plugin:

From fa00bf2ceec6df9ccb1971811562ee88c2989b16 Mon Sep 17 00:00:00 2001
From: Brett Mason <brettsmason@users.noreply.github.com>
Date: Mon, 11 Aug 2025 11:47:44 +0100
Subject: [PATCH 25/25] Fix typo

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 766a7c8..4b32920 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,7 @@ The following filters can be used to override default behaviour/values of brande
 -   `orbit_branded_emails_body_background_color`: Set the body background color of branded emails. Default `woocommerce_email_body_background_color || '#ffffff'`.
 -   `orbit_branded_emails_body_border_color`: Set the border color of branded emails. Default `var(--wp--custom--color--border) || '#edeff1'`.
 -   `orbit_branded_emails_body_text_color`: Set the body text color of branded emails. Default `woocommerce_email_text_color || var(--wp--preset--color--contrast) || '#3f474d'`.
--   `orbit_branded_emails_link_color`: Set the link color color of branded emails. Default `woocommerce_email_base_color || var(--wp--custom--color--link) || '#8549ff'`.
+-   `orbit_branded_emails_link_color`: Set the link color of branded emails. Default `woocommerce_email_base_color || var(--wp--custom--color--link) || '#8549ff'`.
 -   `orbit_branded_emails_footer_text_color`: Set the footer text color of branded emails. Default `woocommerce_email_footer_text_color || var(--wp--preset--color--contrast) || '#3F474d'`.
 -   `orbit_branded_emails_font_family`: Set the font family of branded emails. Default `woocommerce_email_font_family || '"Helvetica Neue", Helvetica, Roboto, Arial, sans-serif'`.
 -   `orbit_branded_emails_logo_image_width`: Set the logo image width in branded emails. Default `woocommerce_email_header_image_width || 120`.