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Cascading Style Sheets (CSS)
is a style
sheet language used
for describing the look
and formatting of
a document written in a markup
language.
While most often used to style web
pages and interfaces written
in HTML and XHTML,
the language can be applied to any kind of XML document,
including plain
XML, SVG and XUL.
CSS is a cornerstone specification of the
web and
almost all web pages use CSS style sheets to
describe their presentation.CSS
is designed primarily to enable the separation
of document content from document presentation,
including elements such as the layout, colors,
and fonts.[1] This
separation can improve content accessibility,
provide more flexibility and control in the
specification of presentation characteristics,
enable multiple pages to share formatting, and
reduce complexity and repetition in the
structural content (such as by allowing for tableless
web design).CSS
can also allow the same markup page to be
presented in different styles for different
rendering methods, such as on-screen, in print,
by voice (when read out by a speech-based
browser or screen
reader)
and on Braille-based,
tactile devices. It can also be used to allow
the web page to display differently depending on
the screen size or device on which it is being
viewed. While the author of a document typically
links that document to a CSS file, readers can
use a different style sheet, perhaps one on
their own computer, to override the one the
author has specified. However if the author or
the reader did not link the document to a
specific style sheet the default style of the
browser will be applied.CSS
specifies a priority scheme to determine which
style rules apply if more than one rule matches
against a particular element. In this so-calledcascade,
priorities or weights are
calculated and assigned to rules, so that the
results are predictable.The
CSS specifications are maintained by the World
Wide Web Consortium (W3C).
Internet media type (MIME
type) text/css is
registered for use with CSS by RFC
2318 (March
1998), and they also operate a free CSS
validation service.[2] |