让table在body下水平、垂直居中

<table   width="100%" border="0" style="height: 100%">
   <tr>
   <td  align="center" valign="middle">

  
<table id="__01" width="994" height="572" border="0" cellpadding="0" cellspacing="0">
    <tr>  <td>内容</td></tr>
    </table>
</td>
</tr>

</table>