CSS is the #2 language of the Internet, and CSS”3” is its most recent iteration. Whereas HTML controls the basic structure and text of a website, CSS controls the colors, the padding and margins, the layout, and on and on.
Håkon Wium Lie is the creator of this language, which had a profound impact and terrific upgrade to the world wide web: this new ability to separate content from styling.
Like HTML, I learned CSS in a classroom at a local college (UCLA) and I couldn't recommend such an opportunity more. That being said, there are some really tight resources that I turn to for the continued education that CSS is:
• I highly recommend Chris Coyier and his website, www.CSS-Tricks.com
• My favorite CSS Book: HTML&CSS design and build websites by John Duckett
• Fast track reading-based learning on the web, I have found this website to be incredible... and free! www.CodeAcademy.com
• I'd be sorely remiss if I didn't mention the "go to" page for getting quick info on anything related to HTML, well, at least it's mygo to: http://www.w3schools.com/
• My last great find for HTML5 has been a free service that checks any page you have online and finds your mistakes, even the small ones that may not show up to your visitors, but might be undermining your coding success in other ways, such as search engine ranking, or how well your web page might be working on other devices: W3C Markup Validation Service http://validator.w3.org