Book HomeCascading Style Sheets: The Definitive GuideSearch this book Sunday 20th of April 2014 02:37:48 AM

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:

@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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child of an ordered list that is itself the child of aBODY. The second list item in the source is thechild of an unordered list, so it can't match the rule.Finally, the third list item in the source is a child of an orderedlist, but the OL element is the child of anLI element, so it doesn't match either.

10.2.1.3. Adjacent-sibling selector

the page background. It is also possible to specify one or more colors in a GIF's palette as transparent.  Here's a link to my <A HREF="mailto:johnmack@udel.edu?subject=Your Awesome MAD-DOG Page!">
e-mail: &nbsp;<IMG ALT="Great Page, Mad Dog!" src=mailbox.gif></a> so you can complain about this page.  The link encloses both 
the image (with default border) and the blue underlined text. Note that I specified the text for the subject line (the sender can change this).

It has been argued that all foreground content is always shown"in front of " all background content, and the behaviorof floated elements seems to support this interpretation. On theother hand, the CSS2 property z-index makes thisreasoning more complicated. As of this writing, implementations havenot yet advanced sufficiently to test this out, and the CSS2description of z-index doesn't really shedany light on this subject.

Ultimately, if you use negative margins, you may not get the same in the specification. The first is for the user agent to create asmall-caps face by scaling uppercase letters on its own. The secondis simply to make all letters uppercase and the same size, exactly asif the declaration text-transform:uppercase; had been used instead, as shown inFigure 5-30. This is obviously not an idealsolution, but it is permitted.

H1 {font-variant: small-caps;}
Figure 5-30

Figure 5-30. Legal, if not optimal, rendering of small caps

all elements

floatIE4 P/B IE5 P/Q NN4 P/P Op3 B/-

Sets thefloat direction for an element. This is generally applied to imagesin order to allow text to flow around them, but under CSS1 anyelement may be floated. Note that, for elements such as paragraph,floating the element will cause its width to tend toward zero unlessan explicit width is assigned; thus, width assignment is a crucialpart of floating any nonreplaced element.