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A
style sheet specifies how certain page-elements should be
displayed, e.g. preferred typefaces, colors, backgrounds.
If no styles are specified, the user's preferences are used,
then the browser's default values (cascading).
Style sheets can be overridden by the user, allowing for individual
needs and preferences.
According
to the specification, styles also follow the principle of
inheritance, i.e. elements inherit their properties
from other elements containing them. Example: a link
in a paragraph will use the same typeface as the whole
paragraph, unless the typeface for links has explicitly been
set differently. But...
Linked
styles vs. embedded styles:
Styles can be placed into an external stylesheet, a file with
.css extension, which makes them re-usable for other
pages. This simplifies maintaining a unified style for a whole
site. Link to them in the HEAD (external styles).
When
styles are unique to a document, but recurring multiple times,
they should be placed directly in the document's HEAD area
(global styles). Styles can also be applied to individual
selections, mostly to override a more general style for a
specific item (local styles).
Styles
can apply to types of document elements, such as headings,
or certain layout tags (e.g. the <em>
tag), or to user-defined classes (e.g. everything you
want to highlight in a specific way). Styles are also an integral
part of Dynamic HTML, via positioning
and visibility attributes.
How do styles work? See next
page.
   
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