Index: wp-includes/css/media-views.css
===================================================================
--- wp-includes/css/media-views.css	(revision 22872)
+++ wp-includes/css/media-views.css	(working copy)
@@ -476,6 +476,7 @@
 	margin: 0 10px 20px;
 	color: #464646;
 	list-style: none;
+	text-align: center;
 
 	-webkit-user-select: none;
 	-moz-user-select:    none;
@@ -507,7 +508,12 @@
 	cursor: pointer;
 }
 
-.attachment .icon,
+.attachment .icon {
+	margin: 0 auto;
+	overflow: hidden;
+	padding-top: 20%;
+}
+
 .attachment .thumbnail {
 	display: block;
 	position: absolute;
@@ -519,12 +525,6 @@
 	max-height: 100%;
 }
 
-/* Vertically center the icons. */
-.attachment .icon {
-	top: 50%;
-	left: 50%;
-}
-
 .attachment-preview .thumbnail:after {
 	content: '';
 	display: block;
@@ -555,7 +555,6 @@
 	transform:         translate( 50%, 50% );
 }
 
-.attachment .icon,
 .attachment .thumbnail .centered img {
 	-webkit-transform: translate( -50%, -50% );
 	-moz-transform:    translate( -50%, -50% );