I suggest the developer tool.If you are using Firefox, Chrome, or IE, you can right-click the element you want to customize (pick some text that you want to change to a different font, for example) and hit F12. That will hive you the developer tools, which will give you a window that shows the CSS file the style affecting your selection comes from, and even which line in the CSS file to look at. Chrome and Firefox make it easy to then poke around and even make some visual changes on the fly (IE, not so easy).