Dimmy, I think you can access the page without the extennsion though. So if you set the alias as style2.css, and the extension is .html, then you can access it using both style2.css or style2.css.html
Hope it will help you having a more common naming for your dynamic css
i just took the simple option and disabled the extention in the config then i set a filename instead of an alias so homepage alias is acctualy index.html instead of just index ect ect, it helped me with creating my robot.txt file and my sitemap.xml file...