For those frustrated with the limited control over document presentation provided by straight HTML markup, Cascading Style Sheets are a welcome advance in web design. Like their counterparts in desktop publishing page-layout programs, style sheets in HTML allow authors to apply typographic styles and spacing instructions for elements on a page. The word cascading refers to what happens when several sources of style information vie for control of the elements on a page—style information is passed down from higher-level style sheets (and from parent to child element within a document) until it is overridden by a style command with more weight. (The cascading rules are discussed in detail later in this chapter.)
This comes as good news for both designers who want more control over presentation, and for HTML purists who stand by the principle that style should be separate from content and structure. Style sheets make both these dreams possible.
We’ve classified style sheets as an “emerging technology” (rather than straight HTML) based on the fact that a low percentage of browsers in current use support them. Furthermore, it is difficult to develop CSS because Netscape and Internet Explorer have implemented them differently and inconsistently. As of this writing, CSS is a promising yet still somewhat risky technology.
Greater typography and page layout controls. With style sheets, you can specify traditional typography attributes ...