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?
Try the developer tools in chrome, using them you can live edit your css definitions. Although I don't know an extension that allows you to reload only a stylesheet, this might work for you when you want to test only a few changes. Firebug for Firefox allows the same thing.