Descendant elements must always have a z-index higher than that of their parent.
<!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' xml:lang='en'>
<head>
<title>The z-index</title>
<style rel='stylesheet' type='text/css'>
body {
background: lightyellow;
}
div.container {
height: 132px;
position: relative;
}
div.zauto {
position: absolute;
border: 1px solid black;
width: 100px;
height: 100px;
}
div.zone {
background: purple;
top: 0;
left: 0;
}
div.ztwo {
background: orange;
top: 10px;
left: 10px;
}
div.zthree {
background: magenta;
top: 20px;
left: 20px;
}
div.zfour {
background: yellow;
top: 30px;
left: 30px;
}
div#nine {
z-index: 4;
}
div#ten {
z-index: 3;
}
div#eleven {
z-index: 2;
}
div#twelve {
z-index: 1;
}
div#nested div {
top: 10px;
left: 10px;
}
div.slide {
float: left;
padding: 5px;
width: 200px;
border: 1px solid rgb(200, 200, 200);
background: white;
margin: 5px;
height: 400px;
}
</style>
</head>
<body>
<div class='slide'>
<div class='container' id='nested'>
<div class='zauto zone' id='nine'>
<div class='zauto ztwo' id='ten'>
<div class='zauto zthree' id='eleven'>
<div class='zauto zfour' id='twelve'></div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>