<html>
<head>
<style>
h3 { border: 2px solid red; padding: 2px; }
</style>
</head>
<body>
In this sample, the H3s should be nested. This matches Firefox, IE, and the HTML5 spec.

<h3><i>One<h3><i>Two<h3><i>Three<h3><i>Four</i></h3></i></h3></i></h3></i></h3>