The firefox extension "web developer" (or "web developer toolbar") has some features to help you identify the CSS stylesheets used by a page, so you can save them ("view css"). It also helps you identify what parts of the stylesheet apply to each feature of the page ("view style information"). Try screwing around with that.
In this specific case, it appears that the page uses
http://www.mandolux.com/aa-style.css for everything.