<!--
     Any copyright is dedicated to the Public Domain.
     http://creativecommons.org/licenses/publicdomain/

     The green square should always be rendered at 100px.
-->
<!DOCTYPE html>
<html>
<head>
<style>
body > div {
  width: 200px;
  height: 200px;
  float: left;
}

body > div > div {
  width: 100px;
  height: 100px;
  background: lime;
}
</style>
</head>
<body style="margin:0">
<div><div></div></div>
<div><div></div></div>
<div><div></div></div>
<div><div></div></div>
<div><div></div></div>
</body>
</html>