table 嵌套时，为什么里面的table不能顶对齐？
<!DOCTYPE html PUBLIC -//W3C//DTD XHTML 1.0 Transitional//EN >
<html xmlns= >
<head>
<meta http-equiv=Content-Type content=text/html; charset=utf-8 />
<title>无标题文档</title>
<style type=text/css>
<!--
.myTable {
padding-top: 0px;
padding-left: 0px;
}
-->
</style>
</head>
<body leftmargin=0 topmargin=0 tracingsrc=media/images/main.jpg tracingopacity=38>
<table width=1005 height=1419 border=0 cellpadding=0 cellspacing=0>
<tr>
<td height=358 valign=top><table width=100% height=255 border=0 align=center cellpadding=0 cellspacing=0 class=myTable >
<tr>
<td height=19> </td>
</tr>
<tr>
<td height=110> </td>
</tr>
<tr>
<td height=21> </td>
</tr>
<tr>
<td height=103> </td>
</tr>
</table></td>
</tr>
<tr>
<td height=916> </td>
</tr>
<tr>
<td height=145> </td>
</tr>
</table>
</body>
</html>
