Network Working Group H. Lie
Request for Comments: 2318 B. Bos
Category: Informational C. Lilley
W3C
March 1998
The text/css Media Type
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved.
Abstract
Cascading Style Sheets (CSS) is a style sheet language for the World
Wide Web. CSS style sheets have been in use since October 1995 using
the Media Type text/css without registration; this memo seeks to
regularize that position.
1. Introduction
The World Wide Web Consortium has issued a Recommendation [1], which
defines Cascading Style Sheets, level 1. This memo provides
information about the text/css Media Type.
2. Cascading Style Sheets
Cascading Style Sheets (CSS) is a style sheet language for the World
Wide Web. It describes the presentation (e.g. fonts, colors and
spacing) of structured documents. CSS is human readable and writable,
and expresses style in common desktop publishing terminology.
CSS style sheets have been in use since October 1995 using the Media
Type text/css without registration; this memo seeks to regularize
that position.
A CSS style sheet can be either:
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(1) external - the style sheet is linked to a document through a
URI and exists as a separate object on the Web. The media type
text/css is used when fetching the object, for example in the
Content-Type and Accept header fields of HTTP [2].
(2) internal - the style sheet is contained within the document. A
typical scenario is an HTML [3] document that contains a style
sheet within the STYLE element. Due to this close relationship,
HTML and CSS share the same top-level name ("text").
4. Registration Information
To: ietf-types@iana.org
Subject: Registration of MIME media type text/css
MIME media type name: text
MIME subtype name: css
Required parameters: none
Optional parameters: charset
The syntax of CSS is expressed in US-ASCII, but a CSS file can
contain strings which may use any Unicode character. Any charset
that is a superset of US-ASCII may be used; US-ASCII, iso-8859-X
and utf-8 are recommended.
Encoding considerations:
For use with transports that are not 8-bit clean, quoted-
printable encoding is recommended since the majority of
characters will be CSS syntax and thus US-ASCII
Security considerations:
Applying a style sheet to a document may hide information
otherwise visible. For example, a very small font size may be
specified, or the display of certain document elements may be
turned off.
CSS style sheets consist of declarative property/value pairs
assigned to element selectors. They contain no executable code.
As with HTML documents, CSS style sheets may contain links to
other media (images, sounds, fonts, other style sheets) and those
links are typically followed automatically by software, resulting
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in the transfer of files without the explicit request of the user
for each one. The security considerations of each linked file are
those of the individual registered types.
Interoperability considerations:
CSS has proven to be widely interoperable across computer
platforms, across Web browsers of different makes, and for import
and export in multiple authoring tools.
Published specification: see [1]
Applications which use this media type:
CSS is device-, platform- and vendor-neutral and is supported by
a wide range of Web user agents and authoring tools for
formatting HTML and XML documents.
Additional information:
Magic number(s): none
File extension(s): .css
Macintosh File Type Code(s): "css "
Object Identifier(s) or OID(s): none
Person & email address to contact for further information:
The authors of this memo.
Intended usage: COMMON
Author/Change controller:
5. References
[1] Lie, H., and B. Bos, "Cascading Style Sheets, level 1",
W3C Recommendation REC-CSS1-961217, http://www.w3.org/TR/REC-
CSS1-961217, December 1996.
[2] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T.
Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC
2068, January 1997.
[3] Raggett, D., Le Hors, A. and I. Jacobs, "HTML 4.0
Specification", W3C Recommendation REC-html40-971218,
http://www.w3.org/TR/REC-html40, December 1997.
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6. Authors' Addresses
Hakon Lie
W3C/INRIA
2004, route des Lucioles - B.P. 93
06902 Sophia Antipolis Cedex
FRANCE
Phone: +33 (0)492387771
Fax: +33 (0)493657765
EMail: howcome@w3.org
Bert Bos
2004, route des Lucioles - B.P. 93
06902 Sophia Antipolis Cedex
FRANCE
Phone: +33 (0)492387692
Fax: +33 (0)493657765
EMail: bert@w3.org
Chris Lilley
2004, route des Lucioles - B.P. 93
06902 Sophia Antipolis Cedex
FRANCE
Phone: +33 (0)492387987
Fax: +33 (0)493657765
EMail: chris@w3.org
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7. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
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RFC, FYI, BCP