how to change font size

How do I change the font size of the title at the top of a category page?

Work your way back from the template file, category.tpl...

You will see that it does not reference any specific stylesheets. Hence it uses default.css (referenced in layout.tpl).

The heading markup in the template file has a class "heading" so you must look for .heading in default.css. When you find it, you will see a font-size entry. If there had not been one, this would be the place to add it.

cheers

Bruce

Get yourself a copy of Firefox Web Developers Tools or Firebug
It makes it alot easier to find which style in which css file you're looking for