Here’s a very sketchy outline of notes on the basic concepts of CSS that need to be understood before getting into the details about applying specific styles to selectors and classes.
- The box model. Padding, borders, margins, colors, backgrounds, display and placement can be manipulated for every element: words, paragraphs, images, divs, body, tables. Understanding the box model is essential to understanding what can be accomplished with CSS.
- The Cascade. Proximity and importance affect results.
- Multiple style sheets. Know when to use linked vs. imported style sheets, as well as how to write style sheets for different media (such as print).
Refer to Eric A Meyer’s Cascading Style Sheets: The Definitive Guide for more about all these concepts.