older user agents that don't know about CSS2, then*.class (or *#id) is an easyway to fool them. Since both of these are examples of invalidselectors in CSS1, they should be ignored by CSS1-only parsers. Ifthey aren't ignored, then they're likely to cause strangeresults. Therefore, it might be a good idea to omit the universalselector in conjunction with class and ID selectors.

BODY > P {color: green;}






Friday 19th of December 2014 01:11:12 PM

by Eric A. Meyer
ISBN 1-56592-622-6
First edition, published May 2000.
(See the catalog page for this book.)

Search the text of Cascading Style Sheets: The Definitive Guide.

Table of Contents

Copyright Page
Preface
Chapter 1: HTML and CSS
Chapter 2: Selectors and Structure
Chapter 3: Units and Values
Chapter 4: Text Properties
Chapter 5: Fonts
Chapter 6: Colors and Backgrounds
Chapter 7: Boxes and Borders
Chapter 8: Visual Formatting
Chapter 9: Positioning
Chapter 10: CSS2: A Look Ahead
Chapter 11: CSS in Action
Appendix A: CSS Resources
Appendix B: HTML 2.0 Style Sheet
Appendix C: CSS1 Properties
Appendix D: CSS Support Chart
Index
Colophon
Library Navigation Links

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

element's box: set the margins to be negative, and the content can overrun the outer edge without technically violating the specification.

There is one important question here, which is this: what happens to the document display when an element is floated out of its parent element by using negative margins? For example, an image could be floated so far up that it intrudes into a paragraph that has already been displayed by the user agent. In this case, it's up to the user agent to decide whether or not the document should be reflowed.is divided in two, with half going above each line, and the other half below. While there is a distance of 16 points between the lines, this is an indirect result of how the extra space is apportioned.

Now let's look at a slightly more complex case. Take the following example:

BODY {font-size: 10pt;}
P {font-size: 18pt; line-height: 23pt;}
BIG {font-size: 250%;}

XML is platform independent, textual information

Information in an XML document is stored in plain-text. This might seem like a restriction if were thinking of embedding binary information in an XML document. There are several advantages to keeping things plain text. First, it is easy to write parsers and all other XML enabling technology on different platforms. Second, it makes everything very interoperable by staying with the lowest common denominator approach. This is the whole reason the web is so successful despite all its flaws. By accepting and sending information in plain text format, programs running on disparate platforms can communicate with each other. This also makes it easy to integrate new programs on top of older ones (without rewriting the old programs), by simply making the interface between the new and old program use XML.

For example, if you have an address book document stored in an XML file, created on a Mac, that you would like to share with someone who has a PC, you can simply email them the plain text address book XML document. This cant be done with binary encoded information which is totally platform (and program) dependent.

Another example is web enabling legacy systems. It is very feasible to create a Java web ennoblement application server that simply uses the services provided by the underlying legacy system. Instead of rewriting the legacy system, if the system can be made to communicate results and parameters through XML, the new and old system can work together without throwing away a company's investment in the legacy system.

to prevent H2 elements from flowing past floatedelements to the left side:

H2 {clear: left;}
Figure 7-74

Figure 7-74. Clear to the left

However, this will allow floated elements to appear on the right sideof H2 elements, as shown in Figure 7-75.

Figure 7-75

Figure 7-75. Clear to the left, but not the right

To avoid this sort of thing, and to make sure that margins, floated elements can appear to protrude out of their parents.

Let's consider once again a floated image which is floated to the left, and which has left and top margins of -15px . This image is placed inside a DIV which has no padding, borders, or margins. The result will be as shown in Figure 8-42.

Figure 8-42

Figure 8-42. Floating with negative margins