<!DOCTYPE HTML>
<html style="height:10%">
<body style="height:100%; margin:0px;padding:0px;">
<table style="height:100%" cellpadding="0px" cellspacing="0px">
 <tr>
  <td style="height: 100%; background: lightblue;">
   Outside the div
   <div style="height:100%">
    <table style="height:100%" cellpadding="0px" cellspacing="0px">
     <tr>
       <td style="height: 100%; background:lightgreen;">
        Inside div
       </td>
     </tr>
    </table>
   </div>
  </td>
 </tr>
</table>
</body>
</html>