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n	 CSS Rationale and Use
n	 Understanding Style Rule Syntax
n	 Style Sheet Types
n	 Application Hierarchy and Sort Order
n	 Hot Tips and more...
As Cascading Style Sheets mature as a language of design
and a tool of Web site and application management, a deep
understanding of how the language really works is essential.
However, most people have learned CSS the same way they’ve
learned HTML—by viewing source, copying template codes,
reading books and articles. While this “bootstrap” method of
learning is often the best way to find great techniques, it may
not be the best for knowing how to manage, debug, customize
and even advance those techniques.
What our training hasn’t necessarily provided are the core
concepts within CSS. This is why the Core CSS series may contain
simple examples of things you already know. You’ll just get to
know them better here! In this foundational reference card, you’ll
find not only a bit of history and rationale for use, rule structure
and syntax, but also a thorough resource as to the Cascade,
inheritance and specificity—core principles of CSS that will expand
and strengthen your professional ability to work with CSS.
The first proposal for CSS was made by Håkom Wium Lie,
now CTO of Opera Software. He worked with Bert Bos to
co-author the first CSS specification, which believe it or not,
became a recommendation in 1996! By 1998 CSS 2.0 brought
us richer options, as we find later in advancing versions CSS
2.1 and CSS 3.0.
As CSS evolves, we find it becoming more and more important
for not only visual designers in terms of managing the esthetics
of the site, but technologists working on large web sites or
looking to create rock-solid applications.
A Separate Piece
The term for sites designed using table-based layouts and HTML
presentation rather than CSS are referred to as being authored
in presentational HTML. This means that the presentation (the