<svg width="300" height="200"
     xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink">
  <desc>This should have a green bar.</desc>
  <defs>
    <rect id="fail" x="0" y="0" width="300" height="200" fill="red"/>
    <rect id="test" width="280" height="20" fill="green"/>
  </defs>
  <rect width="280" height="20" fill="red"/>
  <use xlink:href="#test"/>
</svg>