What is it?
Cascading Style Sheets (CSS) is a style sheet format for HTML
documents endorsed by the World Wide Web Consortium (W3C). It is
used to define layouts, fonts, colours and other aspects of web
document presentation.
When XHTML2 (due in 2007) becomes mainstream, use of stylesheets
will effectively become mandatory. This should make life easier for
web professionals, particularly those maintaining pages that need
updating frequently, since HTML pages themselves will no longer
contain presentational tags.
CSS enables browser and device independence (provided the
browsers are compliant), and the same stylesheets can be used to
define presentation in print, audio (specifying speed,
pronunciation and emphasis) and Braille.
CSS has a simple English-based syntax. It can be used both for
XML and HTML documents, and is also used in conjunction with
Extensible Stylesheet Language (XSL). CSS and XSL use the same
underlying formatting model, and designers can use the same
formatting features in both languages.
Where did it originate?
The idea of stylesheets has been around since the 1970s. The W3C
began thinking about stylesheet languages in 1994. CSS is based on
two proposals: Cascading HTML Stylesheets and Stream-Based
Stylesheets. CSS level 1 emerged in 1996, and level 2 (effectively
the version used today) arrived in 1997.
However, it was not until 2000 that the first browser to provide
full CSS1 support became available. No browser has yet fully
implemented CSS2, and this compromises the goal of full device
independence.
What's it for?
CSS enables presentation to be separated from content.
"Cascading" means that priorities are assigned when conflicting
definitions of presentation are offered by the original designers,
the browser, or users. Users can define presentation to suit their
own preferences and needs.
What makes it special?
Separating presentation from content means that all the pages on
a site can have their appearance changed consistently just by
changing the stylesheet. Documents are smaller and easier to
maintain since they do not contain unique presentational
instructions.
How difficult is it to master?
CSS may have a simple syntax, but in the real world there are
problems with bugs and lack of support - or worse, misrendering of
CSS - in different browsers.
By one estimate, Internet Explorer 6 does not support about 30%
of CSS level 2. This means designers still have to check and test
cross-browser compliance, as they do with HTML pages. Some
authoring tools help with the complexities of CSS use but, as with
browsers, support is patchy.
Training
For Cascading Style Sheets training, the best place to start is
the W3C website. Here you can find tutorials, updates on the
development of CSS, links to external sources, and details of books
and other work by W3C people involved with CSS development, such as
Hakon Wium Lie, Bert Bos and Dave Raggett.
You should not have to spend much the W3C recommends you start
by downloading a CSS-supporting browser (Opera is the obvious one,
but W3C lists many others).
If you find the W3C approach too austere, there are plenty of
alternative free tutorials online.
www.w3.org/Style/CSS/learning
Rates of pay
Cascading Style Sheets experience is needed for many web
developer/designer jobs, and it can also be required with premium
skills such as Adobe/Macromedia Coldfusion. Salaries for web
developers start at £25,000.