diff --git a/assets/css/amp-default.css b/assets/css/amp-default.css
index 2c837e2f469..75df5e14ae3 100644
--- a/assets/css/amp-default.css
+++ b/assets/css/amp-default.css
@@ -1,4 +1,4 @@
-.amp-wp-unknown-size img {
+.amp-wp-unknown-size [src] {
 	/** Worst case scenario when we can't figure out dimensions for an image. **/
 	/** Force the image into a box of fixed dimensions and use object-fit to scale. **/
 	object-fit: contain;
diff --git a/assets/js/amp-editor-blocks.js b/assets/js/amp-editor-blocks.js
index 7b9128f5d3f..2f40feb1a96 100644
--- a/assets/js/amp-editor-blocks.js
+++ b/assets/js/amp-editor-blocks.js
@@ -731,7 +731,7 @@ var ampEditorBlocks = ( function() { // eslint-disable-line no-unused-vars
 					return element;
 				}
 			} else if ( ! component.hasGalleryShortcodeCarouselAttribute( attributes.text || '' ) ) {
-				// Add amp-carousel=false attribut to the shortcode.
+				// Add amp-carousel=false attribute to the shortcode.
 				text = attributes.text.replace( '[gallery', '[gallery amp-carousel=false' );
 			} else {
 				text = attributes.text;
diff --git a/includes/sanitizers/class-amp-audio-sanitizer.php b/includes/sanitizers/class-amp-audio-sanitizer.php
index 4c593a2e124..3622ccb2208 100644
--- a/includes/sanitizers/class-amp-audio-sanitizer.php
+++ b/includes/sanitizers/class-amp-audio-sanitizer.php
@@ -20,6 +20,17 @@ class AMP_Audio_Sanitizer extends AMP_Base_Sanitizer {
 	 */
 	public static $tag = 'audio';
 
+	/**
+	 * Get mapping of HTML selectors to the AMP component selectors which they may be converted into.
+	 *
+	 * @return array Mapping.
+	 */
+	public function get_selector_conversion_mapping() {
+		return array(
+			'audio' => array( 'amp-audio' ),
+		);
+	}
+
 	/**
 	 * Sanitize the <audio> elements from the HTML contained in this instance's DOMDocument.
 	 *
diff --git a/includes/sanitizers/class-amp-base-sanitizer.php b/includes/sanitizers/class-amp-base-sanitizer.php
index 61f3128f6a5..71aaec157a6 100644
--- a/includes/sanitizers/class-amp-base-sanitizer.php
+++ b/includes/sanitizers/class-amp-base-sanitizer.php
@@ -121,6 +121,25 @@ public function __construct( $dom, $args = array() ) {
 		}
 	}
 
+	/**
+	 * Get mapping of HTML selectors to the AMP component selectors which they may be converted into.
+	 *
+	 * @return array Mapping.
+	 */
+	public function get_selector_conversion_mapping() {
+		return array();
+	}
+
+	/**
+	 * Run logic before any sanitizers are run.
+	 *
+	 * After the sanitizers are instantiated but before calling sanitize on each of them, this
+	 * method is called with list of all the instantiated sanitizers.
+	 *
+	 * @param AMP_Base_Sanitizer[] $sanitizers Sanitizers.
+	 */
+	public function init( $sanitizers ) {}
+
 	/**
 	 * Sanitize the HTML contained in the DOMDocument received by the constructor
 	 */
@@ -444,9 +463,6 @@ public function get_data_amp_attributes( $node ) {
 			if ( isset( $parent_attributes['data-amp-noloading'] ) && true === filter_var( $parent_attributes['data-amp-noloading'], FILTER_VALIDATE_BOOLEAN ) ) {
 				$attributes['noloading'] = $parent_attributes['data-amp-noloading'];
 			}
-			if ( isset( $parent_attributes['data-amp-lightbox'] ) && true === filter_var( $parent_attributes['data-amp-lightbox'], FILTER_VALIDATE_BOOLEAN ) ) {
-				$attributes['lightbox'] = true;
-			}
 		}
 
 		return $attributes;
@@ -466,12 +482,6 @@ public function filter_data_amp_attributes( $attributes, $amp_data ) {
 		if ( isset( $amp_data['noloading'] ) ) {
 			$attributes['data-amp-noloading'] = '';
 		}
-		if ( isset( $amp_data['lightbox'] ) ) {
-			$attributes['data-amp-lightbox'] = '';
-			$attributes['on']                = 'tap:' . self::AMP_IMAGE_LIGHTBOX_ID;
-			$attributes['role']              = 'button';
-			$attributes['tabindex']          = 0;
-		}
 		return $attributes;
 	}
 
diff --git a/includes/sanitizers/class-amp-iframe-sanitizer.php b/includes/sanitizers/class-amp-iframe-sanitizer.php
index 07c07875f72..9919783939d 100644
--- a/includes/sanitizers/class-amp-iframe-sanitizer.php
+++ b/includes/sanitizers/class-amp-iframe-sanitizer.php
@@ -48,6 +48,19 @@ class AMP_Iframe_Sanitizer extends AMP_Base_Sanitizer {
 		'add_placeholder' => false,
 	);
 
+	/**
+	 * Get mapping of HTML selectors to the AMP component selectors which they may be converted into.
+	 *
+	 * @return array Mapping.
+	 */
+	public function get_selector_conversion_mapping() {
+		return array(
+			'iframe' => array(
+				'amp-iframe',
+			),
+		);
+	}
+
 	/**
 	 * Sanitize the <iframe> elements from the HTML contained in this instance's DOMDocument.
 	 *
@@ -189,7 +202,7 @@ private function filter_attributes( $attributes ) {
 	private function build_placeholder( $parent_attributes ) {
 		$placeholder_node = AMP_DOM_Utils::create_node( $this->dom, 'div', array(
 			'placeholder' => '',
-			'class' => 'amp-wp-iframe-placeholder',
+			'class'       => 'amp-wp-iframe-placeholder',
 		) );
 
 		return $placeholder_node;
diff --git a/includes/sanitizers/class-amp-img-sanitizer.php b/includes/sanitizers/class-amp-img-sanitizer.php
index 121837d97b8..ba050adc49f 100644
--- a/includes/sanitizers/class-amp-img-sanitizer.php
+++ b/includes/sanitizers/class-amp-img-sanitizer.php
@@ -46,6 +46,20 @@ class AMP_Img_Sanitizer extends AMP_Base_Sanitizer {
 	 */
 	private static $anim_extension = '.gif';
 
+	/**
+	 * Get mapping of HTML selectors to the AMP component selectors which they may be converted into.
+	 *
+	 * @return array Mapping.
+	 */
+	public function get_selector_conversion_mapping() {
+		return array(
+			'img' => array(
+				'amp-img',
+				'amp-anim',
+			),
+		);
+	}
+
 	/**
 	 * Sanitize the <img> elements from the HTML contained in this instance's DOMDocument.
 	 *
@@ -222,15 +236,12 @@ private function adjust_and_replace_node( $node ) {
 		$amp_data       = $this->get_data_amp_attributes( $node );
 		$old_attributes = AMP_DOM_Utils::get_node_attributes_as_assoc_array( $node );
 		$old_attributes = $this->filter_data_amp_attributes( $old_attributes, $amp_data );
+		$old_attributes = $this->maybe_add_lightbox_attributes( $old_attributes, $node );
 
 		$new_attributes = $this->filter_attributes( $old_attributes );
 		$layout         = isset( $amp_data['layout'] ) ? $amp_data['layout'] : false;
 		$new_attributes = $this->filter_attachment_layout_attributes( $node, $new_attributes, $layout );
 
-		if ( isset( $old_attributes['data-amp-lightbox'] ) ) {
-			$this->maybe_add_amp_image_lightbox_node();
-		}
-
 		$this->add_or_append_attribute( $new_attributes, 'class', 'amp-wp-enforced-sizes' );
 		if ( empty( $new_attributes['layout'] ) && ! empty( $new_attributes['height'] ) && ! empty( $new_attributes['width'] ) ) {
 			$new_attributes['layout'] = 'intrinsic';
@@ -248,6 +259,33 @@ private function adjust_and_replace_node( $node ) {
 		$node->parentNode->replaceChild( $new_node, $node );
 	}
 
+	/**
+	 * Set lightbox attributes.
+	 *
+	 * @param array   $attributes Array of attributes.
+	 * @param DomNode $node Array of AMP attributes.
+	 * @return array Updated attributes.
+	 */
+	private function maybe_add_lightbox_attributes( $attributes, $node ) {
+		$parent_node = $node->parentNode;
+		if ( 'figure' !== $parent_node->tagName ) {
+			return $attributes;
+		}
+
+		$parent_attributes = AMP_DOM_Utils::get_node_attributes_as_assoc_array( $parent_node );
+
+		if ( isset( $parent_attributes['data-amp-lightbox'] ) && true === filter_var( $parent_attributes['data-amp-lightbox'], FILTER_VALIDATE_BOOLEAN ) ) {
+			$attributes['data-amp-lightbox'] = '';
+			$attributes['on']                = 'tap:' . self::AMP_IMAGE_LIGHTBOX_ID;
+			$attributes['role']              = 'button';
+			$attributes['tabindex']          = 0;
+
+			$this->maybe_add_amp_image_lightbox_node();
+		}
+
+		return $attributes;
+	}
+
 	/**
 	 * Determines is a URL is considered a GIF URL
 	 *
diff --git a/includes/sanitizers/class-amp-playbuzz-sanitizer.php b/includes/sanitizers/class-amp-playbuzz-sanitizer.php
index 55fb833808c..3ec07e5f8b9 100644
--- a/includes/sanitizers/class-amp-playbuzz-sanitizer.php
+++ b/includes/sanitizers/class-amp-playbuzz-sanitizer.php
@@ -40,6 +40,17 @@ class AMP_Playbuzz_Sanitizer extends AMP_Base_Sanitizer {
 	 */
 	private static $height = '500';
 
+	/**
+	 * Get mapping of HTML selectors to the AMP component selectors which they may be converted into.
+	 *
+	 * @return array Mapping.
+	 */
+	public function get_selector_conversion_mapping() {
+		return array(
+			'div.pb_feed' => array( 'amp-playbuzz.pb_feed' ),
+		);
+	}
+
 	/**
 	 * Sanitize the Playbuzz elements from the HTML contained in this instance's DOMDocument.
 	 *
@@ -113,16 +124,14 @@ private function filter_attributes( $attributes ) {
 					}
 					break;
 
-				case 'data-game-info':
-					$out['data-item-info'] = $value;
-					break;
-
 				case 'data-shares':
 					$out['data-share-buttons'] = $value;
 					break;
 
+				case 'data-game-info':
 				case 'data-comments':
-					$out['data-comments'] = $value;
+				case 'class':
+					$out[ $name ] = $value;
 					break;
 
 				default:
diff --git a/includes/sanitizers/class-amp-style-sanitizer.php b/includes/sanitizers/class-amp-style-sanitizer.php
index 970e2de3c43..1b17b2a65e7 100644
--- a/includes/sanitizers/class-amp-style-sanitizer.php
+++ b/includes/sanitizers/class-amp-style-sanitizer.php
@@ -182,6 +182,13 @@ class AMP_Style_Sanitizer extends AMP_Base_Sanitizer {
 	 */
 	private $processed_imported_stylesheet_urls = array();
 
+	/**
+	 * Mapping of HTML element selectors to AMP selector elements.
+	 *
+	 * @var array
+	 */
+	private $selector_mappings = array();
+
 	/**
 	 * Get error codes that can be raised during parsing of CSS.
 	 *
@@ -308,6 +315,36 @@ private function get_used_tag_names() {
 		return $this->used_tag_names;
 	}
 
+	/**
+	 * Run logic before any sanitizers are run.
+	 *
+	 * After the sanitizers are instantiated but before calling sanitize on each of them, this
+	 * method is called with list of all the instantiated sanitizers.
+	 *
+	 * @param AMP_Base_Sanitizer[] $sanitizers Sanitizers.
+	 */
+	public function init( $sanitizers ) {
+		parent::init( $sanitizers );
+
+		foreach ( $sanitizers as $sanitizer ) {
+			foreach ( $sanitizer->get_selector_conversion_mapping() as $html_selectors => $amp_selectors ) {
+				if ( ! isset( $this->selector_mappings[ $html_selectors ] ) ) {
+					$this->selector_mappings[ $html_selectors ] = $amp_selectors;
+				} else {
+					$this->selector_mappings[ $html_selectors ] = array_unique(
+						array_merge( $this->selector_mappings[ $html_selectors ], $amp_selectors )
+					);
+				}
+
+				// Prevent selectors like `amp-img img` getting deleted since `img` does not occur in the DOM.
+				$this->args['dynamic_element_selectors'] = array_merge(
+					$this->args['dynamic_element_selectors'],
+					$this->selector_mappings[ $html_selectors ]
+				);
+			}
+		}
+	}
+
 	/**
 	 * Sanitize CSS styles within the HTML contained in this instance's DOMDocument.
 	 *
@@ -647,7 +684,7 @@ private function fetch_external_stylesheet( $url ) {
 	private function process_stylesheet( $stylesheet, $options = array() ) {
 		$parsed      = null;
 		$cache_key   = null;
-		$cache_group = 'amp-parsed-stylesheet-v6';
+		$cache_group = 'amp-parsed-stylesheet-v7';
 
 		$cache_impacting_options = array_merge(
 			wp_array_slice_assoc(
@@ -912,6 +949,16 @@ private function prepare_stylesheet( $stylesheet_string, $options = array() ) {
 			$pattern .= preg_quote( $after_declaration_block, '#' );
 			$pattern .= '#s';
 
+			$dynamic_selector_pattern = null;
+			if ( ! empty( $this->args['dynamic_element_selectors'] ) ) {
+				$dynamic_selector_pattern = implode( '|', array_map(
+					function( $selector ) {
+						return preg_quote( $selector, '#' );
+					},
+					$this->args['dynamic_element_selectors']
+				) );
+			}
+
 			$split_stylesheet = preg_split( $pattern, $stylesheet_string, -1, PREG_SPLIT_DELIM_CAPTURE );
 			$length           = count( $split_stylesheet );
 			for ( $i = 0; $i < $length; $i++ ) {
@@ -929,6 +976,11 @@ private function prepare_stylesheet( $stylesheet_string, $options = array() ) {
 						// Remove attribute selectors to eliminate false negative, such as with `.social-navigation a[href*="example.com"]:before`.
 						$reduced_selector = preg_replace( '/\[\w.*?\]/', '', $reduced_selector );
 
+						// Ignore any selector terms that occur under a dynamic selector.
+						if ( $dynamic_selector_pattern ) {
+							$reduced_selector = preg_replace( '#((?:' . $dynamic_selector_pattern . ')(?:\.[a-z0-9_-]+)*)[^a-z0-9_-].*#si', '$1', $reduced_selector . ' ' );
+						}
+
 						$reduced_selector = preg_replace_callback(
 							'/\.([a-zA-Z0-9_-]+)/',
 							function( $matches ) use ( $selector, &$selectors_parsed ) {
@@ -1236,6 +1288,10 @@ private function real_path_urls( $urls, $stylesheet_url ) {
 	private function process_css_declaration_block( RuleSet $ruleset, CSSList $css_list, $options ) {
 		$results = array();
 
+		if ( $ruleset instanceof DeclarationBlock ) {
+			$this->ampify_ruleset_selectors( $ruleset );
+		}
+
 		// Remove disallowed properties.
 		if ( ! empty( $options['property_whitelist'] ) ) {
 			$properties = $ruleset->getRules();
@@ -1754,6 +1810,45 @@ private function finalize_styles() {
 		}
 	}
 
+	/**
+	 * Convert CSS selectors.
+	 *
+	 * @param DeclarationBlock $ruleset Ruleset.
+	 */
+	private function ampify_ruleset_selectors( $ruleset ) {
+		$selectors    = array();
+		$replacements = 0;
+		foreach ( $ruleset->getSelectors() as $old_selector ) {
+			$edited_selectors = array( $old_selector->getSelector() );
+			foreach ( $this->selector_mappings as $html_selector => $amp_selectors ) { // Note: The $selector_mappings array contains ~6 items.
+				$html_pattern = '/(?<=^|[^a-z0-9_-])' . preg_quote( $html_selector ) . '(?=$|[^a-z0-9_-])/i';
+				foreach ( $edited_selectors as &$edited_selector ) { // Note: The $edited_selectors array contains only item in the normal case.
+					$original_selector = $edited_selector;
+					$amp_selector      = array_shift( $amp_selectors );
+					$amp_tag_pattern   = '/(?<=^|[^a-z0-9_-])' . preg_quote( $amp_selector ) . '(?=$|[^a-z0-9_-])/i';
+					preg_match( $amp_tag_pattern, $edited_selector, $matches );
+					if ( ! empty( $matches ) && $amp_selector === $matches[0] ) {
+						continue;
+					}
+					$edited_selector = preg_replace( $html_pattern, $amp_selector, $edited_selector, -1, $count );
+					if ( ! $count ) {
+						continue;
+					}
+					$replacements += $count;
+					while ( ! empty( $amp_selectors ) ) { // Note: This array contains only a couple items.
+						$amp_selector       = array_shift( $amp_selectors );
+						$edited_selectors[] = preg_replace( $html_pattern, $amp_selector, $original_selector, -1, $count );
+					}
+				}
+			}
+			$selectors = array_merge( $selectors, $edited_selectors );
+		}
+
+		if ( $replacements > 0 ) {
+			$ruleset->setSelectors( $selectors );
+		}
+	}
+
 	/**
 	 * Finalize a stylesheet set (amp-custom or amp-keyframes).
 	 *
@@ -1778,16 +1873,6 @@ private function finalize_stylesheet_set( $stylesheet_set ) {
 			) );
 		}
 
-		$dynamic_selector_pattern = null;
-		if ( $should_tree_shake && ! empty( $this->args['dynamic_element_selectors'] ) ) {
-			$dynamic_selector_pattern = '#' . implode( '|', array_map(
-				function( $selector ) {
-					return preg_quote( $selector, '#' );
-				},
-				$this->args['dynamic_element_selectors']
-			) ) . '#';
-		}
-
 		$stylesheet_set['processed_nodes'] = array();
 
 		$final_size = 0;
@@ -1804,8 +1889,6 @@ function( $selector ) {
 					$selectors = array();
 					foreach ( $selectors_parsed as $selector => $parsed_selector ) {
 						$should_include = (
-							( $dynamic_selector_pattern && preg_match( $dynamic_selector_pattern, $selector ) )
-							||
 							(
 								// If all class names are used in the doc.
 								(
diff --git a/includes/sanitizers/class-amp-video-sanitizer.php b/includes/sanitizers/class-amp-video-sanitizer.php
index fdea8947bbd..b61c85343fb 100644
--- a/includes/sanitizers/class-amp-video-sanitizer.php
+++ b/includes/sanitizers/class-amp-video-sanitizer.php
@@ -32,6 +32,17 @@ class AMP_Video_Sanitizer extends AMP_Base_Sanitizer {
 	 */
 	public static $tag = 'video';
 
+	/**
+	 * Get mapping of HTML selectors to the AMP component selectors which they may be converted into.
+	 *
+	 * @return array Mapping.
+	 */
+	public function get_selector_conversion_mapping() {
+		return array(
+			'video' => array( 'amp-video' ),
+		);
+	}
+
 	/**
 	 * Sanitize the <video> elements from the HTML contained in this instance's DOMDocument.
 	 *
diff --git a/includes/templates/class-amp-content-sanitizer.php b/includes/templates/class-amp-content-sanitizer.php
index d9206b427f3..241928d847d 100644
--- a/includes/templates/class-amp-content-sanitizer.php
+++ b/includes/templates/class-amp-content-sanitizer.php
@@ -63,8 +63,16 @@ public static function sanitize_document( &$dom, $sanitizer_classes, $args ) {
 
 		$return_styles = ! empty( $args['return_styles'] );
 		unset( $args['return_styles'] );
+
+		/**
+		 * Sanitizers.
+		 *
+		 * @var AMP_Base_Sanitizer[] $sanitizers
+		 */
+		$sanitizers = array();
+
+		// Instantiate the sanitizers.
 		foreach ( $sanitizer_classes as $sanitizer_class => $sanitizer_args ) {
-			$sanitize_class_start = microtime( true );
 			if ( ! class_exists( $sanitizer_class ) ) {
 				/* translators: %s is sanitizer class */
 				_doing_it_wrong( __METHOD__, sprintf( esc_html__( 'Sanitizer (%s) class does not exist', 'amp' ), esc_html( $sanitizer_class ) ), '0.4.1' );
@@ -84,6 +92,18 @@ public static function sanitize_document( &$dom, $sanitizer_classes, $args ) {
 				continue;
 			}
 
+			$sanitizers[ $sanitizer_class ] = $sanitizer;
+		}
+
+		// Let the sanitizers know about each other prior to sanitizing.
+		foreach ( $sanitizers as $sanitizer ) {
+			$sanitizer->init( $sanitizers );
+		}
+
+		// Sanitize.
+		foreach ( $sanitizers as $sanitizer ) {
+			$sanitize_class_start = microtime( true );
+
 			$sanitizer->sanitize();
 
 			$scripts = array_merge( $scripts, $sanitizer->get_scripts() );
diff --git a/includes/utils/class-amp-dom-utils.php b/includes/utils/class-amp-dom-utils.php
index 552626366f9..e0808303998 100644
--- a/includes/utils/class-amp-dom-utils.php
+++ b/includes/utils/class-amp-dom-utils.php
@@ -473,7 +473,7 @@ public static function create_node( $dom, $tag, $attributes ) {
 	 *
 	 * @since 0.2
 	 *
-	 * @param DOMNode $node Represents an HTML element for which to extract attributes.
+	 * @param DOMElement $node Represents an HTML element for which to extract attributes.
 	 *
 	 * @return string[] The attributes for the passed node, or an
 	 *                  empty array if it has no attributes.
diff --git a/tests/test-amp-img-sanitizer.php b/tests/test-amp-img-sanitizer.php
index ed4f3765f33..f8ec8e1b42e 100644
--- a/tests/test-amp-img-sanitizer.php
+++ b/tests/test-amp-img-sanitizer.php
@@ -180,8 +180,8 @@ public function get_data() {
 			),
 
 			'image_with_custom_lightbox_attrs'         => array(
-				'<img src="http://placehold.it/100x100" width="100" height="100" data-foo="bar" role="button" tabindex="0" data-amp-lightbox="true" />',
-				'<amp-img src="http://placehold.it/100x100" width="100" height="100" data-foo="bar" role="button" tabindex="0" data-amp-lightbox="true" class="amp-wp-enforced-sizes" layout="intrinsic"></amp-img><amp-image-lightbox id="amp-image-lightbox" layout="nodisplay" data-close-button-aria-label="Close"></amp-image-lightbox>',
+				'<figure data-amp-lightbox="true"><img src="http://placehold.it/100x100" width="100" height="100" data-foo="bar" role="button" tabindex="0" /></figure>',
+				'<figure data-amp-lightbox="true"><amp-img src="http://placehold.it/100x100" width="100" height="100" data-foo="bar" role="button" tabindex="0" data-amp-lightbox="" on="tap:amp-image-lightbox" class="amp-wp-enforced-sizes" layout="intrinsic"></amp-img></figure><amp-image-lightbox id="amp-image-lightbox" layout="nodisplay" data-close-button-aria-label="Close"></amp-image-lightbox>',
 			),
 		);
 	}
diff --git a/tests/test-amp-playbuzz-sanitizer.php b/tests/test-amp-playbuzz-sanitizer.php
index 5988dcb9735..430311dacb2 100644
--- a/tests/test-amp-playbuzz-sanitizer.php
+++ b/tests/test-amp-playbuzz-sanitizer.php
@@ -3,50 +3,54 @@
 
 class AMP_Playbuzz_Sanitizer_Test extends WP_UnitTestCase {
 
-    public function get_data() {
-        return array(
-            'no_playbuzz_item' => array(
-                '<h1>Im Not A Playbuzz Embed</h1>',
-                '<h1>Im Not A Playbuzz Embed</h1>',
-            ),
-
-            'playbuzz_item_without_sorce' => array(
-                '<div class="pb_feed"></div>',
-                '<div class="pb_feed"></div>'
-            ),
-
-            'playbuzz_item_with_data_item' => array(
-                '<div class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
-                '<amp-playbuzz data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>'
-            ),
-
-            'playbuzz_item_with_data_game' => array(
-                '<div class="pb_feed" data-game="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right"></div>',
-                '<amp-playbuzz src="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right" height="500"></amp-playbuzz>'
-            ),
-
-            'playbuzz_item_with_data_game_and_data_item' => array(
-                '<div class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" data-game="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right"></div>',
-                '<amp-playbuzz data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" src="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right" height="500"></amp-playbuzz>'
-            ),
-
-            'playbuzz_item_with_data_game_info' => array(
-                '<div class="pb_feed" data-game-info="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
-                '<amp-playbuzz data-item-info="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
-            ),
-
-            'playbuzz_item_with_data_shares_info' => array(
-                '<div class="pb_feed" data-shares="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
-                '<amp-playbuzz data-share-buttons="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
-            ),
-
-            'playbuzz_item_with_data_comments' => array(
-                '<div class="pb_feed" data-comments="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
-                '<amp-playbuzz data-comments="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
-            )
-
-        );
-    }
+	/**
+	 * Data for converter test.
+	 *
+	 * @return array Data.
+	 */
+	public function get_data() {
+		return array(
+			'no_playbuzz_item'                           => array(
+				'<h1>Im Not A Playbuzz Embed</h1>',
+				'<h1>Im Not A Playbuzz Embed</h1>',
+			),
+
+			'playbuzz_item_without_sorce'                => array(
+				'<div class="pb_feed"></div>',
+				'<div class="pb_feed"></div>',
+			),
+
+			'playbuzz_item_with_data_item'               => array(
+				'<div class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
+				'<amp-playbuzz class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
+			),
+
+			'playbuzz_item_with_data_game'               => array(
+				'<div class="pb_feed" data-game="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right"></div>',
+				'<amp-playbuzz class="pb_feed" src="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right" height="500"></amp-playbuzz>',
+			),
+
+			'playbuzz_item_with_data_game_and_data_item' => array(
+				'<div class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" data-game="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right"></div>',
+				'<amp-playbuzz class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" src="https://www.playbuzz.com/jessiemills10/donald-trump-hits-out-at-rachel-maddow-and-accuses-nbc-of-being-fake-news-is-he-right" height="500"></amp-playbuzz>',
+			),
+
+			'playbuzz_item_with_data_game_info'          => array(
+				'<div class="pb_feed" data-game-info="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
+				'<amp-playbuzz class="pb_feed" data-game-info="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
+			),
+
+			'playbuzz_item_with_data_shares_info'        => array(
+				'<div class="pb_feed" data-shares="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
+				'<amp-playbuzz class="pb_feed" data-share-buttons="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
+			),
+
+			'playbuzz_item_with_data_comments'           => array(
+				'<div class="pb_feed" data-comments="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
+				'<amp-playbuzz class="pb_feed" data-comments="true" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121" height="500"></amp-playbuzz>',
+			),
+		);
+	}
 
     /**
      * @dataProvider get_data
diff --git a/tests/test-amp-style-sanitizer.php b/tests/test-amp-style-sanitizer.php
index 8e7b4d8e338..a0f67374fbe 100644
--- a/tests/test-amp-style-sanitizer.php
+++ b/tests/test-amp-style-sanitizer.php
@@ -279,6 +279,7 @@ public function get_link_and_style_test_data() {
 					'<html amp><head><meta charset="utf-8">',
 					'<style amp-custom>b.foo, form [submit-success] b, div[submit-failure] b, form.unused b { color: green }</style>',
 					'<style amp-custom>.dead-list li .highlighted, amp-live-list li .highlighted { background: yellow }</style>',
+					'<style amp-custom>article.missing amp-live-list li .highlighted { background: yellow }</style>',
 					'<style amp-custom>body amp-list .portland { color:blue; }</style>',
 					'</head><body>',
 					'<form method="post" action-xhr="https://example.com/subscribe" target="_top"><div submit-success><template type="amp-mustache"><b>Thanks</b>, {{name}}}</template></div></form>',
@@ -289,6 +290,7 @@ public function get_link_and_style_test_data() {
 				array(
 					'form [submit-success] b,div[submit-failure] b{color:green}',
 					'amp-live-list li .highlighted{background:yellow}',
+					'',
 					'body amp-list .portland{color:blue}',
 				),
 				array(),
@@ -341,6 +343,11 @@ public function test_link_and_style_elements( $source, $expected_stylesheets, $e
 		$actual_stylesheets = array_values( $sanitizer->get_stylesheets() );
 		$this->assertCount( count( $expected_stylesheets ), $actual_stylesheets );
 		foreach ( $expected_stylesheets as $i => $expected_stylesheet ) {
+			if ( empty( $expected_stylesheet ) ) {
+				$this->assertEmpty( $actual_stylesheets[ $i ] );
+				continue;
+			}
+
 			if ( false === strpos( $expected_stylesheet, '{' ) ) {
 				$this->assertContains( $expected_stylesheet, $actual_stylesheets[ $i ] );
 			} else {
@@ -352,6 +359,92 @@ public function test_link_and_style_elements( $source, $expected_stylesheets, $e
 		$this->assertEquals( $expected_errors, $error_codes );
 	}
 
+	/**
+	 * Data for testing AMP selector conversion.
+	 *
+	 * @return array
+	 */
+	public function get_amp_selector_data() {
+		return array(
+			'img' => array(
+				sprintf( '<div><img class="logo" src="%s" width="200" height="100"></div>', admin_url( 'images/wordpress-logo.png' ) ),
+				'div img.logo{border:solid 1px red}',
+				'div amp-img.logo{border:solid 1px red}', // Note amp-anim is still tree-shaken because it doesn't occur in the DOM.
+			),
+			'img-missing-class' => array(
+				sprintf( '<div><img class="logo" src="%s" width="200" height="100"></div>', admin_url( 'images/wordpress-logo.png' ) ),
+				'div img.missing{border:solid 1px red}',
+				'', // Tree-shaken because missing class doesn't occur in the DOM.
+			),
+			'img-and-anim' => array(
+				sprintf( '<div><img class="logo" src="%s" width="200" height="100"><img class="spinner" src="%s" width="200" height="100"></div>', admin_url( 'images/wordpress-logo.png' ), admin_url( 'images/spinner-2x.gif' ) ),
+				'div img{border:solid 1px red}',
+				'div amp-img,div amp-anim{border:solid 1px red}',
+			),
+			'img_with_amp_img' => array(
+				'<amp-img></amp-img>',
+				'amp-img img{background-color:red}',
+				'amp-img img{background-color:red}',
+			),
+			'img-cover' => array(
+				sprintf( '<div><amp-img class="logo" src="%s" width="200" height="100"></amp-img></div>', admin_url( 'images/wordpress-logo.png' ) ),
+				'div amp-img.logo img{object-fit:cover}',
+				'div amp-img.logo img{object-fit:cover}',
+			),
+			'img-tree-shaking' => array(
+				sprintf( '<article><img class="logo" src="%s" width="200" height="100"></article>', admin_url( 'images/wordpress-logo.png' ) ),
+				'div img.logo{border:solid 1px red}',
+				'', // The selector is removed because there is no div element.
+			),
+			'playbuzz' => array(
+				'<p>hello</p><div class="pb_feed" data-item="226dd4c0-ef13-4fee-850b-7be32bf6d121"></div>',
+				'p + div.pb_feed{border:solid 1px blue}',
+				'p + amp-playbuzz.pb_feed{border:solid 1px blue}',
+			),
+			'video' => array(
+				'<article><video src="http://example.com" height="100" width="200"></video></article>',
+				'article>video{border:solid 1px green}',
+				'article>amp-video{border:solid 1px green}',
+			),
+			'video_with_amp_video' => array(
+				'<amp-video class="video"></amp-video>',
+				'amp-video.video video{border:solid 1px green}',
+				'amp-video.video video{border:solid 1px green}',
+			),
+			'iframe' => array(
+				'<p><b>purple</b><iframe src="http://example.com" height="100" width="200"></iframe></p>',
+				'p>*:not(iframe){color:purple}',
+				'p>*:not(amp-iframe){color:purple}',
+			),
+			'audio' => array(
+				'<audio src="http://example.com/foo.mp3" height="100" width="200"></audio>',
+				'audio{border:solid 1px yellow}',
+				'amp-audio{border:solid 1px yellow}',
+			),
+		);
+	}
+
+	/**
+	 * Test AMP selector conversion.
+	 *
+	 * @dataProvider get_amp_selector_data
+	 * @param string $markup Markup.
+	 * @param string $input  Input stylesheet.
+	 * @param string $output Output stylesheet.
+	 */
+	public function test_amp_selector_conversion( $markup, $input, $output ) {
+		$html = "<html amp><head><meta charset=utf-8><style amp-custom>$input</style></head><body>$markup</body></html>";
+		$dom  = AMP_DOM_Utils::get_dom( $html );
+
+		$sanitizer_classes = amp_get_content_sanitizers();
+		$sanitizer_classes['AMP_Style_Sanitizer']['remove_unused_rules'] = 'always';
+		$sanitized   = AMP_Content_Sanitizer::sanitize_document( $dom, $sanitizer_classes, array(
+			'use_document_element' => true,
+		) );
+		$stylesheets = array_values( $sanitized['stylesheets'] );
+		$this->assertEquals( $output, $stylesheets[0] );
+	}
+
 	/**
 	 * Test handling of stylesheets with @font-face that have data: url source.
 	 *