Web Design in a Nutshell, 3rd Edition

Chapter 16. Cascading Style Sheets Fundamentals

Cascading Style Sheets (CSS) is a W3C standard for defining the presentation of web documents. Presentation refers to the way a document is displayed or delivered to the user, whether it’s on a computer monitor, a cell phone display, or read aloud by a screen reader. This book focuses primarily on the visual aspects of presentation, such as typography, colors, alignment, layout, and so on. CSS is the mechanism for providing these types of style instructions to elements in a document that has been marked up with XHTML, HTML, or any XML language. Most important, CSS keeps these presentation instructions separate from the content and its structural and semantic markup.

Before CSS, web designers were at the mercy of the browser’s rendering engine and internal style sheets for the way HTML elements looked in the browser window. Presentational elements and attributes added to HTML, such as the font tag and the bgcolor attribute, granted some additional control over visual display, but the integrity of markup suffered. Cascading Style Sheets (or just “style sheets” in these chapters) hand visual display decisions back to designers and authors. This comes as good news both for designers who want more control over presentation and for those who are eager to see HTML get back to the exclusive business of defining document structure and meaning. Style sheets make both of these goals possible.