I work with web sites a lot, so that means I have to deal with CSS quite a bit.  CSS is notoriously tricky, most web developers might say, but I’ve recently found a good tool that makes CSS work a lot easier: firebug.  I recommend getting it for several reasons:

• Lets you browse HTML code split screen with your rendered HTML, so you can pick a rendered portion of your page and instantly view the corresponding code.
• Shows you only the relevant snippets of CSS code that apply to the selected HTML elements.
• Lets you edit CSS code live, instantly updating the page, without saving those changes to your file(s).
• Shows you which file which piece of CSS came from

I don’t know how I got along with out firebug but my work life is so much easier now when it comes to dealing with css - essential for any web developer in my book.