Index: wp-content/themes/twentytwelve/style.css
===================================================================
--- wp-content/themes/twentytwelve/style.css	(revision 23132)
+++ wp-content/themes/twentytwelve/style.css	(working copy)
@@ -300,7 +300,7 @@
 	background-image: -o-linear-gradient(top, #ebebeb, #e1e1e1);
 	background-image: linear-gradient(top, #ebebeb, #e1e1e1);
 	box-shadow: inset 0 0 8px 2px #c6c6c6, 0 1px 0 0 #f4f4f4;
-	border: none;
+	border-color: transparent;
 }
 li.bypostauthor cite span {
 	color: #fff;
@@ -1724,4 +1724,4 @@
 		margin-left: 50px;
 		margin-left: 3.57142857rem;
 	}
-}
\ No newline at end of file
+}