Book HomeCascading Style Sheets: The Definitive GuideSearch this book Monday 31st of August 2015 05:14:46 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:


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:

@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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Remember that the containing block of an absolutely positionedelement is not necessarily its parent element. In fact, it often isnot, unless the author takes steps to correct this situation.Fortunately, that's easy to do. Just pick the element that youwant to use as the containing block for the absolutely positionedelement, and give it a position ofrelative with no offsets. Thus:

P.contain {position: relative;}

Consider the example in Figure 9-19. It shows two

Most of the time, you'll have no reason to use the keywordtransparent. On occasion, though, it can beuseful. Although it's the default value, users might set theirbrowsers to make all links have a white background. When you designyour page, though, you set anchors to have a white foreground, andyou don't want a background on those anchors. In order to makesure that this happens, you would declare:

A:link {color: white; background-color: transparent;}

If you left out the background color, then your white foreground negative padding lengths.

7.5.1. Percentage Values and Padding

As stated earlier, it's possible toset percentage values for the padding of an element. Percentages arecomputed in relation to the width of the parent element, so they canchange if the parent element's width changes in some way. Forexample, assume the following, which is illustrated in Figure 7-59: border-width. You can also use one of the cousin

Eachof these isused to set the width on a specific border side, of course, just aswith the margin properties.


documents have an inherent structure. In fact, that's part ofthe problem with the Web today: too many of us forget that documentsare supposed to have an internal structure, which is altogetherdifferent than a visual structure. In our rush to create thecoolest-looking pages on the Web, we've bent, warped, andgenerally ignored the idea that pages should contain information thathas some structural meaning.

However, that structure is an inherent part of the relationshipbetween HTML and CSS; without the structure, there couldn't be