The following HTML code formed an email I received from Outlook.com and as you can see it has working CSS styles embedded in it.
I have pasted the code exactly as it appeared (ie. non-tabulated). You might be able to use tabluated HTML code but I cannot be 100% sure. The CSS code inside the <script> tags has been remmed out and this might be intentional.
Try adding your own code and extend this example. I would also mess with all the other elements to see what they do.
HTML
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"><!-- P {margin-top:0;margin-bottom:0;} --></style>
</head>
<body dir="ltr">
<div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;background-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;">
<p>Hello</p>
<p><br>
</p>
<p>From QuantumWarp.com<br>
</p>
</div>
</body>
</html>