Index: wp-admin/includes/template.php
===================================================================
--- wp-admin/includes/template.php	(revision 21022)
+++ wp-admin/includes/template.php	(working copy)
@@ -1675,10 +1675,10 @@
 ?>
 <!DOCTYPE html>
 <!--[if IE 8]>
-<html xmlns="http://www.w3.org/1999/xhtml" class="ie8" <?php do_action('admin_xml_ns'); ?> <?php language_attributes(); ?>>
+<html xmlns="http://www.w3.org/1999/xhtml" class="ie8 toolbar" <?php do_action('admin_xml_ns'); ?> <?php language_attributes(); ?>>
 <![endif]-->
 <!--[if !(IE 8) ]><!-->
-<html xmlns="http://www.w3.org/1999/xhtml" <?php do_action('admin_xml_ns'); ?> <?php language_attributes(); ?>>
+<html xmlns="http://www.w3.org/1999/xhtml" class="toolbar" <?php do_action('admin_xml_ns'); ?> <?php language_attributes(); ?>>
 <!--<![endif]-->
 <head>
 <meta http-equiv="Content-Type" content="<?php bloginfo('html_type'); ?>; charset=<?php echo get_option('blog_charset'); ?>" />
Index: wp-admin/css/wp-admin.dev.css
===================================================================
--- wp-admin/css/wp-admin.dev.css	(revision 21022)
+++ wp-admin/css/wp-admin.dev.css	(working copy)
@@ -1891,9 +1891,11 @@
 /*------------------------------------------------------------------------------
   8.0 - Layout Blocks
 ------------------------------------------------------------------------------*/
-
-body.admin-bar {
+html.toolbar {
 	padding-top: 28px;
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing: border-box;
+	box-sizing: border-box;
 }
 
 .narrow {
