KB FF Firebug
From SWCP Support Wiki
One of the most useful tools available for debugging CSS problems is Firefox's Firebug extension.
It will graphically show you where each CSS box is rendered, how much padding and margin it uses and allow you to temporarily change that CSS to see the effect on your website.
It will also show you just which piece of CSS is responsible for a box's characteristics.
For more information on Firebug check Download here and Firebug website.
