I have tried to get ATOM to format nice with XSL with nearly no success.  So I switched to CSS.  It works!  Almost.  IE6 doesn't render it properly, which is annoying, as I have been a defender of IE for years.  IE7 should do fine.

If you'd like my CSS file, note the xml-stylesheet tag in the XML and grab it.  If you don't know how, then you don't really need it, do you.