http://www.cnblogs.com/oec2003/archive/2007/05/05/736492.html
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>oec2003</title>
<script language="JavaScript" type="text/JavaScript">
<!--
function toggle(targetid){
if (document.getElementById){
target=document.getElementById(targetid);
if (target.style.display=="block"){
target.style.display="none";
} else {
target.style.display="block";
}
}
}
-->
</script>
<style type="text/css">
<!--
#div1{
background-color:#000000;
height:400px;
width:400px;
display:none;
}
-->
</style>
</head>
<body>
<input type="button" id="butn" value="显示/隐藏" οnclick="toggle('div1')" />
<center>
<div id="div1"></div></center>
居中的DIV
</body>
</html>