I have decided I love the Firebug extension in Firefox. It's an absolute life-saver when creating Moodle themes! Saves having to hunt aimlessly through a gazillion (yes, a gazillion) css files to find a bit of code that may or may not be in there because it may be inherited from the parent theme...

So, anyway, yay for Firebug! If you are just getting into developing Moodle themes (or any themes for that matter), You Must Get This. With capital letters.