<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title>CSS: 1 simple test of namespaces (attributes)</title>
  <style type="text/css">
    @namespace html url(http://www.w3.org/1999/xhtml);
    @namespace test url(http://www.example.org/);
    html|body { color: red; }
    [test] { color: green; }
  </style>
 </head>
 <body>
  <test test="test" xmlns="http://www.example.org/">
    This should be green.
  </test>
 </body>
</html>