diff --git a/includes/sanitizers/class-amp-style-sanitizer.php b/includes/sanitizers/class-amp-style-sanitizer.php
index 7628aab3ce8..8fb66ed460a 100644
--- a/includes/sanitizers/class-amp-style-sanitizer.php
+++ b/includes/sanitizers/class-amp-style-sanitizer.php
@@ -28,7 +28,6 @@ private function collect_styles_recursive( $node ) {
 
 			if ( $style ) {
 				$style = $this->process_style( $style );
-
 				if ( ! empty( $style ) ) {
 					$class_name = $this->generate_class_name( $style );
 					$new_class  = trim( $class . ' ' . $class_name );
@@ -58,30 +57,47 @@ private function process_style( $string ) {
 		}
 
 		// Normalize order
-		$arr = array_map( 'trim', explode( ';', $string ) );
-		sort( $arr );
+		$styles = array_map( 'trim', explode( ';', $string ) );
+		sort( $styles );
+
+		$processed_styles = array();
 
-		// Normalize whitespace
-		foreach ( $arr as $index => $rule ) {
+		// Normalize whitespace and filter rules
+		foreach ( $styles as $index => $rule ) {
 			$arr2 = array_map( 'trim', explode( ':', $rule, 2 ) );
-			if ( 2 === count( $arr2 ) ) {
-				$arr[ $index ] = $arr2[0] . ':' . $arr2[1];
+			if ( 2 !== count( $arr2 ) ) {
+				continue;
 			}
+
+			list( $property, $value ) = $this->filter_style( $arr2[0], $arr2[1] );
+			if ( empty( $property ) || empty( $value ) ) {
+				continue;
+			}
+
+			$processed_styles[ $index ] = $property . ':' . $value;
 		}
 
+		return $processed_styles;
+	}
+
+	private function filter_style( $property, $value ) {
 		// Handle overflow rule
 		// https://www.ampproject.org/docs/reference/spec.html#properties
-		if ( $overflow = preg_grep( '/^overflow.*(auto|scroll)$/', $arr ) ) {
-			foreach( $overflow as $index => $rule ) {
-				unset( $arr[ $index ] );
-			}
+		if ( 0 === strpos( $property, 'overflow' )
+			&& ( false !== strpos( $value, 'auto' ) || false !== strpos( $value, 'scroll' ) )
+		) {
+			return false;
+		}
+
+		if ( 'width' === $property ) {
+			$property = 'max-width';
 		}
 
-		return $arr;
+		return array( $property, $value );
 	}
 
 	private function generate_class_name( $data ) {
 		$string = maybe_serialize( $data );
 		return 'amp-wp-inline-' . md5( $string );
 	}
-}
\ No newline at end of file
+}
diff --git a/tests/test-amp-style-sanitizer.php b/tests/test-amp-style-sanitizer.php
index aa6763516b9..c00c80b45af 100644
--- a/tests/test-amp-style-sanitizer.php
+++ b/tests/test-amp-style-sanitizer.php
@@ -30,12 +30,22 @@ public function get_data() {
 			),
 
 			'span_two_styles_reversed' => array(
-				'<span style="width: 350px; color: #00ff00;">This is green.</span>',
-				'<span class="amp-wp-inline-c83b149f3e9c3426a6eab43e21ac2fba">This is green.</span>',
+				'<span style="color: #00ff00; background-color: #000; ">This is green.</span>',
+				'<span class="amp-wp-inline-58550689c128f3d396444313296e4c47">This is green.</span>',
 				array(
-					'.amp-wp-inline-c83b149f3e9c3426a6eab43e21ac2fba' => array(
+					'.amp-wp-inline-58550689c128f3d396444313296e4c47' => array(
+						'background-color:#000',
 						'color:#00ff00',
-						'width:350px',
+					),
+				),
+			),
+
+			'width_to_max-width' => array(
+				'<figure style="width: 300px"></figure>',
+				'<figure class="amp-wp-inline-2676cd1bfa7e8feb4f0e0e8086ae9ce4"></figure>',
+				array(
+					'.amp-wp-inline-2676cd1bfa7e8feb4f0e0e8086ae9ce4' => array(
+						'max-width:300px',
 					),
 				),
 			),
@@ -64,6 +74,17 @@ public function get_data() {
 					),
 				),
 			),
+
+			'existing_class_attribute' => array(
+				'<figure class="alignleft" style="background: #000"></figure>',
+				'<figure class="alignleft amp-wp-inline-3be9b2f79873ad78941ba2b3c03025a3"></figure>',
+				array(
+					'.amp-wp-inline-3be9b2f79873ad78941ba2b3c03025a3' => array(
+						'background:#000',
+					),
+				)
+
+			),
 		);
 	}
 
@@ -83,4 +104,4 @@ public function test_sanitizer( $source, $expected_content, $expected_stylesheet
 		$stylesheet = $sanitizer->get_styles();
 		$this->assertEquals( $expected_stylesheet, $stylesheet );
 	}
-}
\ No newline at end of file
+}