给楼主一个例子作参考
程序代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.">
<html xmlns="http://www.">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>div弹出层</title>
<style type="text/css">
* { margin:0; padding:0;}
#x1 {width:100px; height:100px; background-color:Orange;}
#x2 {width:100px; height:100px; position:absolute; top : 100px; left:0px; background-color:Red;z-index:99}
#x3 { width:100px; height:100px; background-color:Blue; }
</style>
<script>
function cha()
{
document.getElementById("x2").style.display="";
}
function cha1()
{
document.getElementById("x2").style.display="none";
}
</script>
</head>
<body>
<div id="x1" onmouseover="javascript:cha();" onmouseout="javascript:cha1();">
第一层
</div>
<div id="x2" style="display:none">第二层</div>
<div id="x3">第三层</div>
</body>
</html>
2010-12-21 16:38
