<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="application/xhtml+xml; charset=UTF-8" />
<link rel="author" title="Daniel Glazman" href="mailto:d.glazman@partner.samsung.com" />
<title>:root test</title>
<style type="text/css">
html:root { background: green; }
html { background: red; }
p:root { background: red; }
</style>
</head>
<body>
The background of the page should be green and you should see not red at all.
<p>And the background of this sentence should be green too.</p>
</body>
</html>