5.1 Overview of CSS

The purpose of CSS is to allow authors and readers to have greater control over the appearance of HTML documents in browsers. An HTML file can use a style sheet to control the formatting of the document. A style sheet is much like a FrameMaker template; it can specify the fonts, the font sizes, the color, margins, indenting, line height, and so on. A FrameMaker template exists within the FrameMaker document, in its master pages, reference pages, paragraph and character catalogs. A cascading style sheet can exist as a separate file outside the HTML file; the HTML file references the external style sheet. The file extension of style sheets is .css.

Style sheets are combined; the formatting of an HTML document is the result of combining all the style sheets in effect. For example, a document can reference two or more external style sheets. The HTML document can also contain style commands within it; these style commands are combined with all the referenced external style sheets. In addition to the style sheets provided by the author, the browser can provide a style sheet (to be used as the default), and the reader can provide a style sheet. The term cascading is intended to convey the process of combining all the style sheets in effect. The CSS specification defines the rules for combining style sheets.