<html>
<head>
<style type="text/css">
#img1
{
position:absolute;
left:0px;
top:0px;
z-index:-1
}
</style>
<script>
function changeStackOrder()
{
document.getElementById("img1").style.zIndex="1";
}
</script>
</head>
<body>
<h1>This is a Heading</h1>
<img id="img1" src="/demo/bulbon.gif" width="100" height="180">
<input type="button" onclick="changeStackOrder()" value="Change stack order">
<p>Default z-index is 0. Z-index -1 has lower priority.</p>
</body>
</html>