1、DIV固定高度的垂直居中代码：
<style type="text/css">
<!--
div {
position:absolute;
top:50%;
left:50%;
margin:-150px 0 0 -200px;
width:400px;
height:300px;
border:1px solid #008800;
}
-->
</style>
<div>让层垂直居中于浏览器窗口</div>
2、DIV未知高度的垂直居中代码：
<!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>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Vertical centering in valid CSS</title>
<style type="text/css">
body {padding: 0; margin: 0; font-size: 75%; line-height: 140%; font-family:Arial, Helvetica, sans-serif;}
body,html{height: 100%; }
a{color: #333;}
a:hover{color: green;}
#outer {height: 100%; overflow: hidden; position: relative;width: 100%; background:ivory; }
#outer[id] {display: table; position: static;}
#middle {position: absolute; top: 50%;text-align:center;} /* for explorer only*/
#middle[id] {display: table-cell; vertical-align: middle; position: static;}
#inner {position: relative; top: -50%;width: 600px;margin: 0 auto;text-align:left;}/*for explorer only */
div.greenBorder {border: 1px solid green; background-color: #FFF;}
p{margin: 1em;}
</style>
<script type="text/javascript">
// <![CDATA[
function toggleContent(name,n) {
var i,t='',el = document.getElementById(name);
if (!el.origCont) el.origCont = el.innerHTML;
for (i=0;i<n;i++) t += el.origCont;
el.innerHTML = t;
}
// ]]>
</script>
</head>
<body>
<div id="outer">
<div id="middle">
<div id="inner" class="greenBorder">
<p><a href="javascript:toggleContent('inner',1)">默认长度</a> <a href="javascript:toggleContent('inner',2)">加长页面</a></p>
<p> 1.打开illustrator,新建一个文件，画个矩形，比你要导入的图片大一些，白色填充。 <br />
2.选中矩形，菜单：Effect > Distort & Transform > Zig Zag，设置如下图。 <br />
3.菜单：Effect > Stylize > Drop Shadow，设置如下图。 <br />
1.打开illustrator,新建一个文件，画个矩形，比你要导入的图片大一些，白色填充。 <br />
2.选中矩形，菜单：Effect > Distort & Transform > Zig Zag，设置如下图。 <br />
3.菜单：Effect > Stylize > Drop Shadow，设置如下图。</p>
</div>
</div>
</div>
</body>
</html>