<!DOCTYPE html>
<html>
<head>
<style>
div {position: absolute;}
#container div {
background-color: lightblue;
border: 1px solid #333333;
width: 100px;
height: 100px;
opacity: 0.5;
}
div#myBox {
opacity: 1;
background-color: coral;
z-index: 1;
animation: mymove 5s infinite linear;
}
@keyframes mymove {
50% {z-index: 5;}
}
</style>
</head>
<body style="position:absolute">
<h1>Animation of z-index</h1>
<p>Gradually change the z-index property of "myBox" from 1 to 5, and back to 1:<p>
<div id="container">
<div id="myBox">myBox</div>
<div style="top:20px;left:20px;z-index:1;">z-index 1</div>
<div style="top:40px;left:40px;z-index:2;">z-index 2</div>
<div style="top:60px;left:60px;z-index:3;">z-index 3</div>
<div style="top:80px;left:80px;z-index:4;">z-index 4</div>
</div>
</body>
</html>