One of the tools that savvy Web designers use to help them customize sites is called Firebug, a simple Firefox plugin that really holds the key to writing custom CSS and understanding your theme. Firebug gives you all kinds of handy information about your site, including exact CSS definitions that you can use in your custom.css
file.
All-star designer and Thesis user @kristarella has put together a very thoughtful, informative video that will teach you how to use Firebug to customize your site. Be certain to check it out by visiting the video link below!
How to Customize Your Site’s CSS with Firebug
Also, are you following DIYthemes on Twitter? You should be, simply because the team is always sharing Thesis knowledge and information that you won’t want to miss!
Follow @diythemes on Twitter.