Yes, intz is correct. Also lynda dot com is good as well, however, you do have to pay for it, I think it is $25 a month, but it has video tutorials if you are a visual learner.
w3schools is really good because it allows you to practice what they teach you. Lynda.com is also really good but you do have to pay. I would also recommend reading smashingmagazine.com as they have some awesome tips & tricks when it comes to CSS. I visit the site daily and I am still a newbie when it comes to CSS.
Lynda costs money, however. I think they offer free introductory videos. The same thing goes with Think Vitamin, but they're probably a better deal. W3 schools gets you started on learning to use the different languages, and Smashing Magazines goes deeper with tips and tricks. Net tuts plus is another good one.
As I've said many times before... in addition to w3schools and other beginner sites, download the FireBug plugin for FireFox. It will let you learn hands-on by exploring the css/xhtml structure and markup of any site.
I've learned CSS3, JavaScript, HTML5 all from the teacher of them all, Lynda Training Tutorials They're so awesome at Lynda and they give you very useful tips that are useful on a long term basis. You can either buy their tutorials for supporting them financially or you could also download their tutorials via torrents, I would suggest buying it though.