yige.org 试一个

<html>
<head>
<style type="text/css">
#img1
{
position:absolute;
left:0px;
top:0px;
z-index:-1
}
</style>
<script type="text/javascript">
function changeStackOrder()
{
document.getElementById("img1").style.zIndex="1";
}
</script>
</head>
<body>

<h1>This is a Heading</h1>

<img id="img1" src="/static/images/bulbon.gif">

<p>Default z-index is 0. Z-index -1 has lower priority.</p>

<input type="button" onclick="changeStackOrder()" value="Change stack order" />

</body>
</html>

结果:

编辑上面的代码，点击查看结果。

yige.org - 试一个