WWW5: HTML and cascading style sheets

HTML:

this session started with a "big bang": the announcement of HTML V3.2 ! the day before, it seemed there was no future for the HTML standard and now they pictured it bright and full of hope.

recent history:

the "HTML working group" (HTML-WG) of the "Internet Engineering Task Force " (IETF) proposed a standard for HTML V2.0 in RFC 1866. in the meantime, tables, style sheets etc. were developed, but there was no consents on the style mechanism for example. because there was little involvement by the market leaders, the HTML-WG was about to be shut down. the W3C set up a "Editorial Review Board" (ERB) to watch the various developments and the idea came up to provide a means to register HTML-extensions rather than defining a new standard.

then the W3C managed to set up a meeting between Spyglass, Netscape and Microsoft. working drafts about objects, layout etc. were written. the initial meeting was followed by many weekly telephone conferences.

in the end, HTML V3.0 was dead, but V3.2 was developed together with IBM, Microsoft, Netscape, Novell, Pathfinder, SoftQuad, Spyglass and Sun.

HTML V3.2:

HTML V3.2 includes many widely deployed features such as tables, background colors etc. while providing full backward compatibility with HTML V2.0 !

the future of HTML:

the following extensions are under consideration:

• OBJECT-tag: it shall replace and streamline various tags to support the inclusion of inline images, animations, videos, Java applets etc.
• math: there is a need to support mathematical expressions which allows to capture meaning and presentation.
• printing: there should be a separate style guide for printing, fonts shall be downloadable, there is a need for improved color handling and the author should have more control over the print process. in addition, a collection of documents should be treated as one single document as far as printing is concerned.

cascading style sheets:

there is obviously a need to give the author more control over the presentation of her or his document. there are various ways to approach this:

• new tags, such as CENTER or FONTS
• new formats, such as PDF (Portable Document Format)
• new paradigms, such as Java
• or style sheets

style sheets separate presentation from contents. they preserve the document's structure and provide device independency.

DSSSL versus CSS:

there are two approaches to style sheets:

1. DSSSL: Document Style Semantics and Specification Language, which is quite heavy and paper oriented

1. CSS: Cascading Style Sheets are much lighter and screen oriented

CSS are simple and human readable. they replace all commonly used HTML extensions.

implementation:

there are three ways to apply a style to a document:

1. as a link: <LINK REL=STYLESHEET TYPE="text" HREF="any URL">
2. style statements inside the document: H1 { color : red }
3. via attributes: <H1 STYLE=COLOR:RED>xxx</H1> (not recommended !)

scalability:

style sheets will provide various types of scalability:

• attributes
• screen to screen (adapting to different screen sizes, gamma correction)
• screen versus paper
• visual versus non-visual (access to disabled people)

cascading:

the term "cascading" implies that there might be multiple style sheets for one document. there might come a style sheet with the document and the reader may have her or his own style sheet especially suited for a particular screen or any other output device. conflicts must be resolved by the browser.

the future of style sheets:

in the future, style sheets might be extended to support:

• multiple media, such as voice or paper
• a fully developed layout language
• more properties
• environmental influences (e.g. document aging)

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