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 at all, because the lack of a border-style in the second rule means that the default value of none will be used. As we've seen, that will turn the border off altogether.
With all of this shorthand stuff, you're probably starting to suspect that it goes even further, and you're right. We finally come to the shortest shorthand border property of all: border. 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.
The following typographical conventions are used in this book:
is used to indicate code examples, HTML tags and CSS elements.
is used for replaceables that appear in text.
is used to introduce new terms and to indicate URLs, filenames, and pathnames.
indicates a note or tip relating to the nearby text.
indicates a warning.
Copyright © 2002 O'Reilly & Associates. All rights reserved.float.
For example, to float an image to the right, you could use thismarkup:<IMG SRC="b5.gif" style="float: right;" alt="section b5">
As Figure 7-63 makes clear, the image "floats" towould have appeared is simply closed up, and the positioned textoverlaps the some of the content. There is no way to avoid this,short of positioning the boldfaced text outside of the paragraph (byusing a negative value for right) or by specifyinga padding for the paragraph that is wide enough to accommodate thepositioned element. Also, since it has a transparent background, theparent element's text shows through the positioned element. Theonly way to avoid this is to set a background for the positionedelement.won't affect the placement of the origin image.
18.104.22.168. Interesting effects
In technical terms, when abackground image has been set to be fixed, it ispositioned with respect to the viewing area, not the element thatcontains it. However, the background will only be visible within itscontaining element. This leads to a rather interesting consequence.paragraph that precedes it. It is also impossible for a floated element's top to be any higher than the top of a floated element that occurs earlier. Figure 8-34 is an example of this.
Figure 8-34. Keeping floats below their predecessors
6. A floating element's top may not be higher than the top of any line box with content that precedes the floating element.