Introduction to CSS (Cascading Style Sheets)
http://www.webdesignfromscratch.com/introduction-to-css.cfm

Hunt, Ben
Web Design From Scratch
2006

Abstract:

CSS (Cascading Style Sheets) is a smart way to add styling information to web pages. While it's possible to add styling to HTML (e.g. using the tag) HTML should only be used to structure your content, CSS is the only way you should apply styling.