CSS: The Definitive Guide, 3rd Edition

If you are a web designer or document author interested in sophisticated page styling,
improved accessibility, and saving time and effort, 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 to follow
this book.

This third edition of
CSS:
The Definitive Guide
covers CSS2 and CSS2.1 (up through the 11 April
2006 Working Draft), the latter of which is, in many ways, a clarification of the first.
While some CSS3 modules have reached Candidate Recommendation status as of this writing, I
have chosen not to cover them in this edition (with the exception of some CSS3 selectors).
I made this decision because implementation of these modules is still incomplete or
nonexistent. I feel it's important to keep the book focused on currently supported and
well-understood levels of CSS, and to leave any future capabilities for future editions.

Throughout this book, there are boxes that break down a
given CSS property. These have been reproduced practically verbatim from the CSS
specifications, but some explanation of the syntax is in order.

Throughout, the allowed values for each property are listed with the following
syntax:

Any words between "<" and ">" give a type of value or a reference to another
property. For example, the property
font
will accept
values that actually belong to the property
font-family
. This is denoted by the text . Any words
presented in
constant width
are keywords that must
appear literally, without quotes. The forward slash (/) and the comma (,) must also be
used literally.

Several keywords strung together means that all of them must occur in the given
order. For example,
help me
means that the property
must use those keywords in that exact order.

If a vertical bar separates alternatives (X | Y), then any one of them must occur. A
vertical double bar (X || Y) means that X, Y, or both must occur, but they may appear in
any order. Brackets ([...]) are for grouping things together. Juxtaposition is stronger
than the double bar, and the double bar is stronger than the bar. Thus "V W | X || Y Z"
is equivalent to "[ V W ] | [ X || [ Y Z ]]".

Every word or bracketed group may be followed by one of the following modifiers:

Some examples follow:

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We appreciate, but do not require, attribution. An attribution usually includes the
title, author, publisher, and ISBN. For example: "
CSS: The Definitive
Guide
, Third Edition, by Eric A. Meyer. Copyright 2007 O'Reilly Media, Inc.,
978-0-596-52733-4."

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[email protected]
.

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I'd like to take a moment to thank the people who have backed me up during the long
process of getting this book to its readers.

First, I'd like to thank everyone at O'Reilly for all they've done over the years,
giving me my break into publishing and continuing to give me the opportunity to produce
a book that matters. For this third edition, I'd like to thank Tatiana Apandi for her
good humor, patience, and understanding as I played chicken with my deadlines.

I'd also like to thank most profoundly my technical reviewers. For the first edition,
that was David Baron and Ian Hickson, with additional input from Bert Bos and Håkon Lie.
The second edition was reviewed by Tantek Çelik and Ian Hickson. The fine folks who
performed technical review on the third edition, the one you hold in your hands, were
Darrell Austin, Liza Daly, and Neil Lee. All lent their considerable expertise and
insight, keeping me honest and up-to-date on the latest changes in CSS as well as taking
me to task for sloppy descriptions and muddled explanations. None of the editions, least
of all this one, could have been as good as it is without their collective efforts, but
of course whatever errors you find in the text are my fault, not theirs. That's kind of
a cliché, I know, but it's true nonetheless.

Similarly, I'd like to thank everyone who pointed out errata that needed to be
addressed. I may not have always been good about sending back email right away, but I
read all of your questions and concerns and, when needed, made corrections. The
continued feedback and constructive criticism will only help the book get better, as it
always has.

There are a few personal acknowledgments to make as well.

To the staff of WRUW, 91.1 FM Cleveland, thank you for nine years of support, great
music, and straight-out fun. Maybe one day I'll bring Big Band back to your airwaves,
and maybe not; but either way, keep on keepin' on.

To Jeffrey Zeldman, thanks for being a great colleague and partner; and to the whole
Zeldman family, thanks for being such wonderful friends.

To "Auntie" Molly, thanks for always being who you are.

To "Uncle" Jim, thanks for everything, both professionally and personally. It's no
exaggeration to say I wouldn't be where I am without your influence, and our lives would
be a good deal poorer without you around.

To the Bread and Soup Crew—Jim, Genevieve, Jim, Gini, Ferrett, Jen, Jenn, and
Molly—thanks for all your superb cooking and tasty conversation.

To my extended family, thank you as always for your love and support.

To anyone I should have thanked, but didn't: my apologies. And my thanks.

And to my wife and daughter, more thanks than I can ever express for making my days
richer than I have any right to expect, and for showering me with more love than I could
ever hope to repay. Though I'll keep trying, of course.