HTML, XHTML, and CSS Bible, Fifth Edition

Chapter 25. CSS Basics

IN THIS CHAPTER

• The Purpose of Styles

• Styles and HTML

• CSS Levels 1, 2, and 3

• Defining Styles

• Cascading Styles

The Web was founded on HTML and plain-text documents. Over the last few years the Web has become a household and industrial mainstay, maturing into a viable publishing platform thanks in no small part to Cascading Style Sheets (CSS).

CSS enables Web authors and programmers to finely tune elements for publishing both online and across several different types of media, including print format. This chapter serves as the introduction to CSS. Subsequent chapters in this section will show you how to use styles with specific elements.

The Purpose of Styles

Styles are an electronic publishing invention for dynamically coding text and other document elements with formatting. For example, a style called "Heading" would be attached to every heading in the document. The style definition would contain information about how headings should be formatted. In this book, for example, headings (such as "The Purpose of Styles," above) use a larger, bold font.

Note

Anyone who has spent an appreciable amount of time in and around a word-processing program has no doubt encountered styles. The concept of styles used by word processors does not differ appreciably from that of CSS and the Web—if you understand the former, you should have a good grasp on usage of the latter.

The advantage of styles is that you can change a definition once and that change affects every element using that ...