Apply a subtle semi-transparent border to images in the media list table to avoid the "white on white (like a polar bear in Antarctica)" problem.

Props ericlewis.
Fixes #15860.


git-svn-id: https://develop.svn.wordpress.org/trunk@28842 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/common.css

@@ -1653,6 +1653,7 @@ td.media-icon {
 }
 
 td.media-icon img {
+	border: 1px solid rgba(0, 0, 0, 0.07);
 	max-width: 80px;
 	max-height: 60px;
 }