When I\'m working with CSS, I\'ll often test in a browser - say, Chrome - right click an element, click Inspect Element, and edit the CSS right there. The use of arrow keys
Firediff is a Firebug add-on that tracks changes done in Firebug. It logs everything you'll do in the HTML pane (great) but also your brief use of the Web Developer Toolbar extension (not so great), say Shift-Ctrl-F to obtain a font-size information in px.
I have seen a Firebug extension in Chrome but didn't test it, I use Firediff with Firefox.