Cascading Style Sheets

Cascading Style Sheets (CSS)
CSS3 logo and wordmark.svg
Filename extension
.css
Internet media type
text/css
Uniform Type Identifier (UTI)public.css
Developed by
Initial releaseDecember 17, 1996 (1996-12-17)
Type of formatStyle sheet language
Standards
Websitewww.w3.org/Style/CSS/

Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language like HTML.[1] CSS is a cornerstone technology of the World Wide Web, alongside HTML and JavaScript.[2]

CSS is designed to enable the separation of presentation and content, including layout, colors, and fonts.[3] This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple web pages to share formatting by specifying the relevant CSS in a separate .css file, and reduce complexity and repetition in the structural content.

Separation of formatting and content also makes it feasible to present the same markup page in different styles for different rendering methods, such as on-screen, in print, by voice (via speech-based browser or screen reader), and on Braille-based tactile devices. CSS also has rules for alternate formatting if the content is accessed on a mobile device.[4]

The name cascading comes from the specified priority scheme to determine which style rule applies if more than one rule matches a particular element. This cascading priority scheme is 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). The W3C operates a free CSS validation service for CSS documents.[5]

In addition to HTML, other markup languages support the use of CSS including XHTML, plain XML, SVG, and XUL.

  1. ^ "CSS developer guide". Mozilla Developer Network. Archived from the original on 2015-09-25. Retrieved 2015-09-24.
  2. ^ Flanagan, David. JavaScript - The definitive guide (6 ed.). p. 1. JavaScript is part of the triad of technologies that all Web developers must learn: HTML to specify the content of web pages, CSS to specify the presentation of web pages, and JavaScript to specify the behaviour of web pages.
  3. ^ "What is CSS?". World Wide Web Consortium. Archived from the original on 2010-11-29. Retrieved 2010-12-01.
  4. ^ "Web-based Mobile Apps of the Future Using HTML 5, CSS and JavaScript". HTMLGoodies. Archived from the original on 2014-10-20. Retrieved 2014-10-16.
  5. ^ "W3C CSS validation service". Archived from the original on 2011-02-14. Retrieved 2012-06-30.

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