<html>
<head>
<style>
div { width:100px; height:100px }
.green { background-color: green }
.red { background-color: red }
</style>
</head>
<body>

You should see a green square below.

<div class="red" style="position:relative; z-index:0">
  <div class="red" style="position:absolute; z-index:auto">
    <div class="red" style="position:absolute; z-index:inherit">
      <div class="green" style="position:absolute; z-index:1000">
      </div>
    </div>
  </div>
  <div class="red" style="position:absolute; z-index:100">
  </div>
</div>
</body>
</html>