W3C CSS2 Cascading Style Sheets, level 2 - instructional media + ...

Note. In CSS2, it is not possible to refer to attribute values for other
elements of the selector.
The ’display’ property controls whether the content is placed in a block, inline,
or marker box.
Authors should put ’content’ declarations in @media [p. 78] rules when the
content is media-sensitive. For instance, literal text may be used for any media
group, but images only apply to the visual + bitmap media groups, and sound
files only apply to the aural media group.
Example(s):
The following rule causes a sound file to be played at the end of a quotation
(see the section on aural style sheets [p. 277] for additional mechanisms):
@media aural {
BLOCKQUOTE:after { content: url("beautiful-music.wav") }
}
Example(s):
The next rule inserts the text of the HTML "alt" attribute before the image. If the
image is not displayed, the reader will still see the "alt" text.
IMG:before { content: attr(alt) }
Authors may include newlines in the generated content by writing the "\A"
escape sequence in one of the strings after the ’content’ property. This inserts a
forced line break, similar to the BR element in HTML. See "Strings" [p. 50] and
"Characters and case" [p. 38] for more information on the "\A" escape sequence.
Example(s):
H1:before {
display: block;
text-align: center;
content: "chapter\A hoofdstuk\A chapitre"
}
Generated content does not alter the document tree. In particular, it is not fed
back to the document language processor (e.g., for reparsing).
Note. In future levels of CSS, the ’content’ property may accept additional
values, allowing it to vary the style of pieces of the generated content, but in
CSS2, all the content of the :before or :after pseudo-element has the same style.
12.3 Interaction of :before and :after with
’compact’ and ’run-in’ elements
The following cases can occur:
1. A ’run-in’ or ’compact’ element has a :before pseudo-element of type
’inline’: the pseudo-element is taken into account when the size of the
element’s box is computed (for ’compact’) and is rendered inside the same
block box as the element.
2. A ’run-in’ or ’compact’ element has an :after pseudo-element of type
’inline’: The rules of the previous point apply.
3. A ’run-in’ or ’compact’ element has a :before pseudo-element of type
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