<!DOCTYPE html>
<html>
<body>

<div style="display:-moz-deck">
  <div>
    <span style="float: right; width: 0;">x</span>
  </div>
  <div style="position: relative;">
    <span style="float: right;">
      <span style="position: absolute;">y</span>
    </span>
  </div>
</div>

</body>
</html>