Internet Explorer 5+, Firefox, Opera, Safari
<body>
<!--[if lt IE 6]><div id="crapper"><![endif]-->
<h1>Heading</h1>
<p>And some content</p>
<!--[if lt IE 6]></div><![endif]-->
</body>Good browsers can style the body element. IE5 (crap browser) needs a wrapper; crapper. Internet Explorer 6 in quirks mode needs this wrapper as well. Use <!--[if lte IE 6]> in that case.
Check the source for the CSS.