div垂直居中

<style type="text/css">
<!--
* {margin:0;padding:0}
div {
  width:500px;
  height:500px;
  border:1px solid #666;
  overflow:hidden;
  position:relative;
  display:table-cell;
  text-align:center;
  vertical-align:middle
}
div p {
  position:static;
  +position:absolute;
  top:50%
  }
img {
  position:static;
  +position:relative;
  top:-50%;left:-50%;
  }
-->
</style>
<div><p><img src="http://www.google.com/intl/en/images/logo.gif" /></p></div>