<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body> <div id="test" style="position: absolute; background-color: #FF0000;">12345</div>
<script language="JavaScript" type="text/javascript">
div4= document.getElementById('test');
div4.style.left=Math.floor(screen.availWidth/2-200)+'px'
</script>
</body>
</html>