<html>
<head>
<style>
.pad { padding: 50%; }
</style>
</head>

<body>
 <table cellspacing=0 cellpadding=0>
   <tr>
     <td><div class="pad">a</div></td>
     <td><div class="pad">b</div></td>
   </tr>
 </table>
</body>

</html>