Index: src/wp-admin/css/common.css
===================================================================
--- src/wp-admin/css/common.css	(revision 34093)
+++ src/wp-admin/css/common.css	(working copy)
@@ -1981,6 +1981,7 @@
 	margin-right: 190px;
 }
 
+.metabox-holder h2,
 .metabox-holder h3 {
 	font-size: 14px;
 	padding: 8px 12px;
@@ -1988,6 +1989,12 @@
 	line-height: 1.4;
 }
 
+/* backwards compatibility with current nav-menus screen */
+.nav-menus-php .metabox-holder h3 {
+	padding: 10px 10px 11px 14px;
+	line-height: 21px;
+}
+
 #templateside ul li a {
 	text-decoration: none;
 }
@@ -3357,7 +3364,7 @@
 		font-size: 14px;
 	}
 
-	.metabox-holder h3 {
+	.metabox-holder h2 {
 		padding: 12px;
 	}
 
Index: src/wp-admin/css/dashboard.css
===================================================================
--- src/wp-admin/css/dashboard.css	(revision 34093)
+++ src/wp-admin/css/dashboard.css	(working copy)
@@ -947,12 +947,12 @@
 	box-shadow: none;
 }
 
-#dashboard_browser_nag.postbox.browser-insecure h3 {
+#dashboard_browser_nag.postbox.browser-insecure h2 {
 	border-bottom-color: #cd5a5a;
 	color: #fff;
 }
 
-#dashboard_browser_nag.postbox h3 {
+#dashboard_browser_nag.postbox h2 {
 	border-bottom-color: #f6e2ac;
 	background: transparent none;
 	color: #fff;
@@ -966,7 +966,7 @@
 
 /* Make the browser nags easier to read with Open Sans */
 
-#dashboard_browser_nag h3.hndle {
+#dashboard_browser_nag h2.hndle {
 	border: none;
 	font-weight: 600;
 	font-size: 20px;
Index: src/wp-admin/css/edit.css
===================================================================
--- src/wp-admin/css/edit.css	(revision 34093)
+++ src/wp-admin/css/edit.css	(working copy)
@@ -616,14 +616,7 @@
 	position: absolute;
 }
 
-#poststuff h2 {
-	margin-top: 20px;
-	font-size: 1.5em;
-	margin-bottom: 15px;
-	padding: 0 0 3px;
-	clear: left;
-}
-
+#poststuff h2,
 #poststuff h3 {
 	font-size: 14px;
 	padding: 8px 12px;
@@ -1347,6 +1340,7 @@
 		padding: 10px 10px;
 	}
 
+	#poststuff h2,
 	#poststuff h3 {
 		padding: 12px;
 	}
Index: src/wp-admin/includes/template.php
===================================================================
--- src/wp-admin/includes/template.php	(revision 34093)
+++ src/wp-admin/includes/template.php	(working copy)
@@ -1100,7 +1100,7 @@
 						echo '<span class="screen-reader-text">' . sprintf( __( 'Click to toggle %s panel' ), $box['title'] ) . '</span><br />';
 						echo '</button>';
 					}
-					echo "<h3 class='hndle'><span>{$box['title']}</span></h3>\n";
+					echo "<h2 class='hndle'><span>{$box['title']}</span></h2>\n";
 					echo '<div class="inside">' . "\n";
 					call_user_func($box['callback'], $object, $box);
 					echo "</div>\n";