<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>document.documentElement.offsetHeight</script>
</head>
<body>
<div style="height: 3000px; background: lightgreen;"/>
<div style="width: 4px; float: left; background: yellow;">
A
<span style="padding: 5px">
<span style="float: left;" />
</span>
Z
</div>
</body>
</html>