If you are learning CSS, or need a refresher, here are some tutorial sites. I know there are others, maybe more popular, but if I go to a site that is supposed to be teaching CSS and their code is all messed up, I will not post the link.
If you are already up and going with CSS, here are some helpers, or cheats, that can make life a little easier. Again, I tried to go for the printable ones, and one is even a widget from Apple. (There are times I wish I had a mac again. I feel a Mac Pro calling my name, uh-oh.)