<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title>background on non-HTML body should not fill the viewport</title>
  <style>
   html { background-color:transparent; background-image:none; }
   body { background-color:red; }
   p { background-color:lime; margin:0; }
  </style>
  <script>
   window.onload = function() {
     var oldElm = document.getElementsByTagName("body")[0];
     var newElm = document.createElementNS("urn:foo:bogus", "body");
     while (oldElm.firstChild)
       newElm.appendChild(oldElm.firstChild);
     document.documentElement.replaceChild(newElm, oldElm);
     document.getElementsByTagName("p")[0].firstChild.data = "This line should be green and there should be no red.";
   }
  </script>
 </head>
 <body>
  <p>FAIL (script didn't run)</p>
 </body>
</html>