<!DOCTYPE html>
Test passes if above is on top.
<table cellspacing="0" cellpadding="0">
  <caption>
    <div style="position:relative; height:2em;">
      <div id="elm" style="position:absolute; left:0;">above</div>
    </div>
  </caption>
  <tr>
    <td>below</td>
  </tr>
</table>

<script>
onload = function() {
  document.body.offsetTop;
  document.getElementById('elm').style.left = '1px';
}
</script>