sites that help you to refresh css and html

I am digging into the YUI and prototype-rico.
It is time to give html/css a systematic (re)treatment.
Here a site:

http://www.w3schools.com/css/showit.asp?filename=ex1


I know, there are so many there, and books. However, I do not believe we need books here. Come on, you are a programmer, and it is just html/css! Seriously, books are no good here for the following reasons:
(a) Most books on this are for dummies, or, for academics, either way, bad for programmers.
(b) Online resources are very good – inherently -- you can see it in action.

This site is good, because it is to-the-point (O'Reilly style, if you may).

Other sites (google css reference or css tutorial)

http://htmlhelp.com/reference/css/quick-tutorial.html
http://htmlhelp.com/reference/css/
http://www.css-ref.com/
http://www.html.net/tutorials/css/
http://www.westciv.com/style_master/academy/css_tutorial/