Enclose CSS in HTML comment tag

it is recommended that you enclose your CSS declarations in a HTML comment tag because with browsers that don’t recognize <style></style>, the tags within them might not get ignored completely and could cause potential problems for the HTML file.

<style type="text/css">
<!--
@import url(sheet2.css);
h1 {color: maroon;}
body {background: yellow;}
-->
</style>

By Bryan Xu