Book HomeCascading Style Sheets: The Definitive GuideSearch this book Monday 25th of July 2016 07:50:09 PM

10.8. Media Types and @-rules

Don't get too excited yet. We aren't talking about media types in the sense of things like audio and video authoring. Well, not exactly, anyway. We're talking about creating rules for presentation within various kinds of media. The defined types of media thus far are:

These are all values of @media, one of several new @-rules. Some others are:

10.8.1. Paged Media

Since I just brought up paged media, I should probably mention that there are some new properties that apply to such media. Five of them apply to page breaks and where they appear:

page-break-before
page-break-after
page-break-inside
orphans
widows 

The first two are used to control whether a page break should appear before or after a given element, and the latter two are common desktop publishing terms for the minimum number of lines that can appear at the end or beginning of a page. They mean the same thing in CSS2 as they do in desktop publishing.

page-break-inside (first proposed by this author, as it happens) is used to define whether or not page breaks should be placed inside a given element. For example, you might not want unordered lists to have page breaks inside them. You would then declare UL {page-break-inside: avoid;}. The rendering agent (your printer, for example) would avoid breaking unordered lists whenever possible.

There is also size, which is simply used to define whether a page should be printed in landscape or portrait mode and the length of each axis. If you plan to print your page to a professional printing system, you might want to use marks, which can apply either cross or crop marks to your page. Thus you might declare:

@page {size: 8.5in 11in; margin: 0.5in; marks: cross;}

This will set the pages to be U.S. letter-standard, 8.5 inches wide by 11 inches tall, and place cross marks in the corners of each page.

In addition, there are the new pseudo-classes :left , :right, and :first, all of which are applied only to the @page rule. Thus, you could set different margins for left and right pages in double-sided printing:

@page:left {margin-left: 0.75in; margin-right: 1in;}
@page:right{margin-left: 1in; margin-right: 0.75in;} 

The :first selector applies only to the first page of a document, so that you could give it a larger top margin or a bigger font size:

you need to pick a style and declare it.

7.4.3. Border Colors

Compared to the other aspects of borders, setting the color is pretty easy. In CSS1, there is the single property border-color,

@page:first {margin-top: 2in; font-size: 150%;}

10.8.2. The Spoken Word

To round things out, we'll cover some of the properties in the area of aural style sheets. These are properties that help define how a speaking browser will actually speak the page. This may not be important to many people, but for the visually impaired, these properties are a necessity.

First off, there is voice-family, which is much the same as font-family in its structure: the author can define both a specific voice and a generic voice family. There are several properties controlling the speed at which the page is read (speech-rate), as well as properties for the pitch , pitch-range, stress, richness, and volume of a given voice. There are also properties that let you control how acronyms, punctuation, dates, numerals, and time are spoken. There are ways to specify audio cues, which can be played before, during, or after a given element (such as a hyperlink), ways to insert pauses before or after elements, and even the ability to control the apparent position in space from which a sound comes via the properties azimuth and elevation. With these last two properties, you could define a style sheet where the text is read by a voice "in front of" the user, whereas background music comes from "behind" and audio cues come from "above" the user!



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You'll remember that I said the second-simplest rule ofhorizontal formatting was this: the total of the seven horizontalproperties always equals the width of the parentelement. At first glance, this can be interpreted to mean that anelement can never be wider than its parent's contentarea -- and as long as all properties are zero or greater,that's quite true. However, consider the following, depicted inFigure 8-19:

igure 8-19. Wider children through negative margins
P {color: maroon;}EM {color: #999999;}
Figure 6-9

Figure 6-9. Different colors for different elements

Thanks to the inheritability of color, it's theoretically possible toset all of the ordinary text in a document to be a color such as redby declaring BODY {color:red;}. This should cause all text which is not otherwisestyled (such as anchors, which have their own color styles) to bered. This should not affect elements such as horizontal rules (HR ) or images. However, early versions of