Index: wp-admin/includes/theme.php
===================================================================
--- wp-admin/includes/theme.php	(revision 26518)
+++ wp-admin/includes/theme.php	(working copy)
@@ -197,9 +197,10 @@
 			'right-sidebar' => __( 'Right Sidebar' ),
 		),
 
-		__( 'Width' ) => array(
-			'fixed-width'    => __( 'Fixed Width' ),
-			'flexible-width' => __( 'Flexible Width' ),
+		__( 'Layout' ) => array(
+			'fixed-layout'      => __( 'Fixed Layout' ),
+			'flexible-layout'   => __( 'Flexible Layout' ),
+			'responsive-layout' => __( 'Responsive Layout' ),
 		),
 
 		__( 'Features' ) => array(