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Chapter 8. Cascading Style Sheets
Style sheets are the way
publishing professionals manage the overall
"look" of their
publications backgrounds, fonts, colors, and so on from a
single page to huge collections of documents. Most desktop-publishing
software supports style sheets, as do popular word processors, so the
necessity of style sheets for HTML documents was obvious.
From the start, HTML focused on
content over style. Authors are encouraged to worry about providing
high-quality information and leave it to the browser to worry about
presentation. We strongly urge you to adopt this philosophy in your
documents don't mistake style for substance.
However, presentation is for the benefit of the reader, and even the
original designers of HTML understood the interplay between style and
readability for example, through the physical style and header
tags. Style sheets extend that presentation with several additional
effects, including colors, a wider selection of fonts, and even
sounds so that users can better distinguish elements of your
document. But most importantly, style sheets let you control the
presentation attributes for all the tags in a document for a
single document or a collection of many documents from a single
master.
In
early 1996, the World Wide Web Consortium (W3C) put together a draft
proposal defining Cascading Style Sheets (CSS) for HTML. This draft
proposal quickly matured into a recommended standard. In mid-1998,
the W3C extended the original specification to create
CSS2, which includes presentation
standards for a variety of media besides the familiar onscreen
browser, along with a several other enhancements.
Currently, no browser or web agent fully complies with the CSS2
standard. However, because we realize that eventual compliance with
the W3C standard is likely, we'll cover all the
components of the CSS2 standard in this chapter, even if they are not
yet supported by any browser. As always, we'll
denote clearly what is real, what is proposed, and what is actually
supported.[1]
[1] In the fall of 2000, work began on CSS3.
As CSS3 is still under construction and browsers have not yet even
become fully compliant with CSS2, we focus on CSS2 throughout this
chapter.
