<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title>CSS Positioning: Containing Block of Top Level Absolutely Positioned Elements</title>
  <style type="text/css">
   html { margin: 0; border: 0; padding: 0; background: white; color: yellow; }
   body { margin: 1em; border: 1em solid red; padding: 1em; background: maroon; color: yellow; }
   p { margin: 1em; padding: 1em; }
   div { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: green; color: white; }
  </style>
 </head>
 <body>
  <p>FAIL</p>
  <p>This page should be completely green.</p>
  <div>There should be no red on this page.</div>
  <!-- the <div> element should exactly overlap the <html> element,
  since they have the same dimensions and the same containing block
  and the same origin. -->
 </body>
</html>