Book HomeCascading Style Sheets: The Definitive GuideSearch this book Thursday 23rd of March 2017 09:02:46 PM


The subject of this book is, as you might have guessed by the cover, Cascading Style Sheets (CSS). There are two "levels" to CSS; these are referred to as CSS1 and CSS2. The difference between the two is that CSS2 is all of CSS1, plus a lot more. This book attempts to cover all of CSS1, and CSS positioning, which is a part of CSS2. The rest of CSS2 is excluded because, at the time of this writing, nobody had implemented most of it. Rather than cover a lot of theoretical territory, we chose to stick to what was currently usable.

If you are a web designer or document author interested in sophisticated page styling, improved accessibility, and saving time and effort, then this book is for you. All you really need before starting the book is a decent knowledge of HTML 4.0. The better you know HTML, of course, the better prepared you'll be. You will need to know very little else in order to follow this book.

It is important to remember something about web standards and books: the former are continually evolving, while the latter are frozen in time (until the next edition comes out, anyway). In the case of HTML and CSS, there are a great many changes afoot even as these words are being written. The recent formalization of XHTML 1.0 as a full W3C Recommendation, for example, is a major milestone in the evolution of the World Wide Web. There are likely to be even more levels to CSS, further extending the ability to style documents; major web browsers are approaching full CSS1 support, and robust CSS2 implementations can be seen lurking on the horizon. This is an exciting time to be a designer, and learning CSS now will give you a leg up on the future.

0.1. Typographical Conventions

The following typographical conventions are used in this book:

Constant width

is used to indicate code examples, HTML tags and CSS elements.

Constant width italic

is used for replaceables that appear in text.

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Now, thanks to the power of CSS, you can have many, many differentcolors within a single page, and without using a singleFONT tag. This gives authors the ability to set uppages where the main text is black with a white background, but thenavigational hyperlinks along the side of the page are black on alight purple background. There are almost infinite possibilities:defining red text for warnings, using a dark purple to make boldfacedtext even more obvious, setting each heading to be a different shadeof green, and on and on. following:

H4 {border-style: dashed solid double;}H4 {border: medium green;}

This will result in H4 elements having no borderat all, because the lack of a border-style in the second rule meansthat the default value of none will be used. Aswe've seen, that will turn the border off altogether.