(Это приложение является
информативным, а не формальным)
The goal of the work on CSS1 has been to create a
simple style sheet mechanism for HTML documents. The current
specification is a balance between the simplicity needed to
realize style sheets on the web, and pressure from authors for
richer visual control. CSS1 offers:
visual markup replacement: HTML extensions, e.g.
"CENTER", "FONT" and
"SPACER", are easily replaced with CSS1 style
sheets.
nicer markup: instead of using "FONT"
elements to achieve the popular small-caps style, one
declaration in the style sheet is sufficient. Compare the
visual markup:
<H1>H<FONT SIZE=-1>EADLINE</FONT></H1>
with the style sheet:
H1 { font-style: small-caps }
<H1>Headline</H1>
various integration levels: CSS1 style rules can
be fetched from external style sheets, included in the
'STYLE' element, or put into 'STYLE' attributes. The
latter option offers easy transition from HTML
extensions.
new effects: some new visual effects have been
added to offer users new toys. The typographical
pseudo-elements and the extra values on the background
property fall into this category.
scalability: CSS1 will be useful on equipment
ranging from text terminals to high-resolution color
workstations. Authors can write one style sheet and be
reasonably sure that the intended style will come across
in the best possible manner.
CSS1 does not offer:
per pixel control: CSS1 values simplicity over
level of control, and although the combination of
background images and styled HTML is powerful, control to
the pixel level is not possible.
author control: the author cannot enforce the use
of a certain sheet, only suggest
a layout language: CSS1 does not offer multiple
columns with text-flow, overlapping frames etc.
a rich query language on the parse tree: CSS1 can
only look for ancestor elements in the parse tree, while
other style sheet languages (e.g. DSSSL [6] ) offers a
full query language.
We expect to see extensions of CSS in several
directions:
paper: better support for printing HTML documents
support for non-visual media: work is in the
process to add a list of properties and corresponding
values to support speech and braille output
color names: the currently supported list may be
extended
fonts: more precise font specification systems
are expected to complement existing CSS1 font properties.
values, properties: we expect vendors to propose
extensions to the CSS1 set of values and properties.
Extending in this direction is trivial for the
specification, but interoperability between different UAs
is a concern
layout language: support for two-dimensional
layout in the tradition of desktop publishing packages.
other DTDs: CSS1 has some HTML-specific parts
(e.g. the special status of the 'CLASS' and 'ID'
attributes) but should easily be extended to apply to
other DTDs as well.
We do not expect CSS to evolve into:
a programming language
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(,
,
), All Rights Reserved. W3C
,
and rules apply.
