<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Testcase</title>
<style type="text/css">
div { background: red; }
span { float: left; }
</style>
</head>
<body>
<div>
<span>There should be no red</span>
</div>
</body>
</html>
Prince will incorrectly make the div tall enough to contain one line box, even though it should have 0 height (no matter how tall you make the contents of the float).
If you add this rule:
div { height: 0; }
The div will become 1px high (as seen in Adobe reader 7.0).
Both of these mean that margin collapsing around floats is all wrong, and strange gaps appear above the content that follows it. Tested in 6.0r1 on Windows XP.