I want to learn Web UI design. (I know, I know. Being a programmer puts me at a disadvantage. But I want to try anyway.) Thus, I would like to "debug" my CSS files.

Once of the biggest annoyances I have found is that I cannot test a change in my CSS files without reloading the whole page. Sometimes, the page is too big. Sometimes, a lot of elements were brought to the page after lots of clicks, because my pages rely too heavily on AJAX. Sometimes, I just hate hitting Command+R all the time.

Is there any extension for any of the major browsers (preferably Safari and/or Chrome) that re-renders the page using an updated version of the CSS file, without reloading the whole page itself?