I’ve just posted this elsewhere but I think Firebug for Firefox will help a lot 🙂
The Firebug extension (http://getfirebug.com/) for Firefox (and Chrome) is fantastic for finding and viewing the exact styles etc that you are modifying. This page explains how to do it: http://www.bloggingpro.com/archives/2010/08/02/how-to-easily-edit-your-wordpress-theme-design-with-the-firebug-firefox-addon/
Firebug is a lifesaver in so far as time goes – wonderful! Oh, and so is Child Themes in WordPress.
Jonathan
