Book HomeCascading Style Sheets: The Definitive GuideSearch this book Monday 24th of October 2016 01:57:41 AM

A.3. Online Communities

One can read only so much before it comes time to join a discussion and ask some questions. There are two major venues for discussions about CSS, but each is concerned with a specific type of discussion -- so make sure you go to the right place.

A.3.1. comp.infosystems.www.authoring.stylesheets

This Usenet group, often abbreviated as ciwas (pronounced "see-wass"), is the gathering place for CSS authors. A number of

Obviously, the latter rule in each pair is much simpler to type and edit, and you'll probably use such rules in most circumstances.

If you want an exact match, you can use an ordinary attribute selector. Thus, the following rule:

<P CLASS="driving directions" >This is a side note (and it's green).</P>

If you aren't quite so concerned about exact matching, you can string class selectors together. This is a new feature of CSS2, and with this approach, you can match a class experts in the field check this newsgroup regularly, this author among them, and all are there for one primary reason: to help new CSS authors over the hurdles that learning any new language will generate. The secondary reason is for the spirited debates that occasionally erupt over some aspect of CSS, or a browser's implementation thereof. Rather unusually for a newsgroup, the signal-to-noise ratio stayed fairly high for the last few years of the 1990s, and will with any luck continue in that vein.


Anyone who wishes to be involved in discussing the future course of CSS, and to clearing up ambiguities in the specifications, should subscribe to this list. The members of the list are all, in one fashion or another, interested in making CSS better than it is already. Please note: www-style is not the place to ask for assistance with writing CSS. For help with CSS authoring problems, visit ciwas instead. Questions beginning with "How do I ... ?" are frowned upon by the regulars of www-style and are usually redirected to a more appropriate forum such as ciwas. On the other hand, questions that begin "Why can't I ... ?" or "Wouldn't it be cool if ... ?" are generally welcome, so long as they relate to some ability that appears to be missing from CSS.

Messages to www-style are only accepted if the sender is already subscribed to the list. In order to subscribe, send email to with the word subscribe in the subject of the message; to unsubscribe, send email to with the word unsubscribe in the subject of the message.

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Copyright © 2002 O'Reilly & Associates. All rights reserved. Percentage values

Closely related to the keywords arepercentage values, although they behave in a rather interesting way.Let's say that you want to center a background image within itselement by using percentage values. That's easy enough:

BODY {background-image: url(bigyinyang.gif);background-repeat: no-repeat;background-position: 50% 50%;}

This causes the background image to be placed such that its center is