<!DOCTYPE HTML>
<style>
  html     { height: 50%; }
  body     { height:100%; }
  table    { height:100%; }
  div      { height:100%; }
  td.green { background:lightgreen }
  td.fill  { height: 100% }
</style>
<html>
<body>
  <table cellpadding="0" cellspacing="0">
    <tr>
      <td class="fill"><div>
        <table cellpadding="0" cellspacing="0">
          <tr><td class="green">foo</td></tr>
        </table>
      </div></td>
    </tr>
  </table>
</body>
</html>