<svg xmlns="http://www.w3.org/2000/svg"
     xmlns:xlink="http://www.w3.org/1999/xlink"
     width="100" height="50">
  <style>use:not(:target) { display: none; }</style>
  <defs>
    <rect id="green-box" fill="#00ff00" width="100" height="50"/>
    <rect id="red-box" fill="#ff0000" width="100" height="50"/>
  </defs>
  <use id="green" xlink:href="#green-box"/>
  <use id="red" xlink:href="#red-box"/>
</svg>