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 designed primarily to enable the
separation of document content from document
presentation, including elements such as the layout, colors,
and fonts.
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).
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-called cascade, priorities or weights are
calculated and assigned to rules, so that the
results are predictable.
