diff --git src/wp-admin/css/widgets.css src/wp-admin/css/widgets.css
index 2f34ae6882..267df0e7d5 100644
--- src/wp-admin/css/widgets.css
+++ src/wp-admin/css/widgets.css
@@ -110,7 +110,7 @@
 	background-color: #fbfbfc;
 	border-style: solid;
 	border-color: #5b9dd9;
-	box-shadow: 0 0 3px rgba( 0, 115, 170, .8 );
+	box-shadow: 0 0 3px rgba(0, 115, 170, 0.8);
 	/* Only visible in Windows High Contrast mode */
 	outline: 2px solid transparent;
 	outline-offset: -2px;
@@ -133,6 +133,25 @@
 .media-widget-control .media-widget-preview img {
 	max-width: 100%;
 	vertical-align: middle;
+	background-image: linear-gradient(
+			45deg,
+			#c4c4c4 25%,
+			transparent 25%,
+			transparent 75%,
+			#c4c4c4 75%,
+			#c4c4c4
+		),
+		linear-gradient(
+			45deg,
+			#c4c4c4 25%,
+			transparent 25%,
+			transparent 75%,
+			#c4c4c4 75%,
+			#c4c4c4
+		);
+	background-position: 0 0, 10px 10px;
+	background-size: 20px 20px;
+	width: 100%;
 }
 .media-widget-control .media-widget-preview .wp-video-shortcode {
 	background: #000;
@@ -163,7 +182,7 @@
 }
 
 .media-widget-video-link .dashicons {
-	font: normal 60px/1 'dashicons';
+	font: normal 60px/1 "dashicons";
 	position: relative;
 	width: 100%;
 	top: -90px;
@@ -217,11 +236,17 @@
  * See: https://alistapart.com/article/quantity-queries-for-css
  */
 .media-widget-gallery-preview .gallery-item:nth-last-child(3):first-child,
-.media-widget-gallery-preview .gallery-item:nth-last-child(3):first-child ~ .gallery-item,
-.media-widget-gallery-preview .gallery-item:nth-last-child(n+5),
-.media-widget-gallery-preview .gallery-item:nth-last-child(n+5) ~ .gallery-item,
-.media-widget-gallery-preview .gallery-item:nth-last-child(n+6),
-.media-widget-gallery-preview .gallery-item:nth-last-child(n+6) ~ .gallery-item {
+.media-widget-gallery-preview
+	.gallery-item:nth-last-child(3):first-child
+	~ .gallery-item,
+.media-widget-gallery-preview .gallery-item:nth-last-child(n + 5),
+.media-widget-gallery-preview
+	.gallery-item:nth-last-child(n + 5)
+	~ .gallery-item,
+.media-widget-gallery-preview .gallery-item:nth-last-child(n + 6),
+.media-widget-gallery-preview
+	.gallery-item:nth-last-child(n + 6)
+	~ .gallery-item {
 	max-width: 33.33%;
 }
 
@@ -252,7 +277,6 @@
 	color: white;
 }
 
-
 /* Widget Dragging Helpers */
 .widget.ui-draggable-dragging {
 	min-width: 100%;
@@ -327,9 +351,7 @@
 }
 
 .sidebar-name .handlediv:focus .toggle-indicator:before {
-	box-shadow:
-		0 0 0 1px #5b9dd9,
-		0 0 2px 1px rgba(30, 140, 190, 0.8);
+	box-shadow: 0 0 0 1px #5b9dd9, 0 0 2px 1px rgba(30, 140, 190, 0.8);
 }
 
 .sidebar-name h2,
@@ -539,10 +561,10 @@ div#widgets-right .closed .widgets-sortables {
 .widget-control-edit {
 	display: block;
 	color: #666;
-	background: #EEE;
+	background: #eee;
 	padding: 0 15px;
-	line-height: 3.30769230;
-	border-left: 1px solid #DDD;
+	line-height: 3.3076923;
+	border-left: 1px solid #ddd;
 }
 
 #widgets-left .widget-control-edit:hover,
@@ -634,7 +656,6 @@ div#widgets-right .closed .widgets-sortables {
 	cursor: default;
 }
 
-
 /* Widgets Area Chooser */
 .widget-liquid-left #widgets-left.chooser #available-widgets .widget,
 .widget-liquid-left #widgets-left.chooser .inactive-sidebar {
@@ -648,7 +669,10 @@ div#widgets-right .closed .widgets-sortables {
 	pointer-events: none;
 }
 
-.widget-liquid-left #widgets-left.chooser #available-widgets .widget-in-question {
+.widget-liquid-left
+	#widgets-left.chooser
+	#available-widgets
+	.widget-in-question {
 	/* -webkit-filter: none; */
 	opacity: 1;
 	pointer-events: auto;
@@ -769,7 +793,8 @@ div#widgets-right .widget-top:hover,
 ul.CodeMirror-hints {
 	z-index: 101; /* Due to z-index 100 set on .widget.open */
 }
-.widget-control-actions .custom-html-widget-save-button.button.validation-blocked {
+.widget-control-actions
+	.custom-html-widget-save-button.button.validation-blocked {
 	cursor: not-allowed;
 }