The website says it's supported however the following style does not render.
<style type="text/css">
a[href="#"]{outline:#f00 dotted 2px !important}
</style>
however, the following will render
<style type="text/css">
a[href="#"]{border:#f00 dotted 2px !important}
</style>
Here is my document
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>...</title>
<link type="text/css" rel="stylesheet" href="../content/style.css" />
</head>
<body>...</body>
</html>