Index: src/wp-admin/css/admin-menu.css
===================================================================
--- src/wp-admin/css/admin-menu.css	(revision 46632)
+++ src/wp-admin/css/admin-menu.css	(working copy)
@@ -204,7 +204,7 @@
 .folded #adminmenu a.wp-has-current-submenu:focus + .wp-submenu,
 .folded #adminmenu .wp-has-current-submenu .wp-submenu {
 	padding: 7px 0 8px;
-	z-index: 9999;
+	z-index: 999;
 	background-color: #32373c;
 	box-shadow: 0 3px 5px rgba(0, 0, 0, 0.2);
 }
Index: src/wp-admin/css/themes.css
===================================================================
--- src/wp-admin/css/themes.css	(revision 46632)
+++ src/wp-admin/css/themes.css	(working copy)
@@ -366,7 +366,7 @@
 	bottom: 0;
 	background: #f1f1f1;
 	background: rgba(238, 238, 238, 0.9);
-	z-index: 10000; /* Over WP Pointers. */
+	z-index: 997; /* Over WP Pointers. */
 }
 
 .theme-overlay .theme-header {
@@ -473,7 +473,7 @@
 	bottom: 3%;
 	background: #fff;
 	box-shadow: 0 1px 20px 5px rgba(0, 0, 0, 0.1);
-	z-index: 10000; /* Over WP Pointers. */
+	z-index: 998; /* Over WP Pointers. */
 	box-sizing: border-box;
 	-webkit-overflow-scrolling: touch;
 }