Index: wp-content/themes/twentythirteen/css/ie.css
===================================================================
--- wp-content/themes/twentythirteen/css/ie.css	(revision 23955)
+++ wp-content/themes/twentythirteen/css/ie.css	(working copy)
@@ -60,6 +61,21 @@
 	max-width: 604px;
 	margin: 0;
 }
+
+.gallery-item,
+.gallery img {
+	max-width: none;
+}
+
+.gallery-caption {
+	background: #000;
+	filter: alpha(opacity=0);
+}
+
+.gallery-item:hover .gallery-caption {
+	filter: alpha(opacity=70);
+}
+
 .comment {
 	clear: both;
 }
@@ -117,10 +133,6 @@
 	width: auto;
 }
 
-.ie8 .gallery img {
-	max-width: none;
-}
-
 .ie8 .sidebar .entry-header,
 .ie8 .sidebar .entry-content,
 .ie8 .sidebar .entry-summary,