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:

(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").

3. 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 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:

References

Authors' Addresses

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 implementation 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 assignees.

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.

Acknowledgment

Funding for the RFC Editor function is currently provided by the Internet Society.