<!DOCTYPE html>
<!-- Any copyright is dedicated to the Public Domain.
- http://creativecommons.org/publicdomain/zero/1.0/ -->
<html>
<style>
div#details {
background-color: orange;
width: 500px;
height: 200px;
}
div#summary {
background-color: green;
width: 50%;
}
div#in_summary {
position: absolute;
background-color: green;
top: 60px;
left: 100px;
width: 150px;
height: 100px;
}
div#before_summary {
position: absolute;
background-color: cyan;
top: 50px;
left: 50px;
width: 150px;
height: 100px;
z-index: 1;
}
</style>
<body>
<div id="details">
<div id="before_summary">div before summary</div>
<div id="summary">Summary<div id="in_summary">div in summary</div></div>
</div>
</body>
</html>