Приложение E: Применимость и расширяемость CSS1. Спецификация CSS1
(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:
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
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
) 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
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:
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