17-08-2012, 12:34 PM
Cascading Style Sheets, level 2 CSS2 Specification
Cascading Style.pdf (Size: 1.52 MB / Downloads: 23)
Abstract
This specification defines Cascading Style Sheets, level 2 (CSS2). CSS2 is a
style sheet language that allows authors and users to attach style (e.g., fonts,
spacing, and aural cues) to structured documents (e.g., HTML documents and
XML applications). By separating the presentation style of documents from the
content of documents, CSS2 simplifies Web authoring and site maintenance.
CSS2 builds on CSS1 (see [CSS1]) and, with very few exceptions, all valid
CSS1 style sheets are valid CSS2 style sheets. CSS2 supports media-specific
style sheets so that authors may tailor the presentation of their documents to
visual browsers, aural devices, printers, braille devices, handheld devices, etc.
This specification also supports content positioning, downloadable fonts, table
layout, features for internationalization, automatic counters and numbering, and
some properties related to user interface.
Status of this document
This document has been reviewed by W3C Members and other interested parties
and has been endorsed by the Director as a W3C Recommendation. It is a stable
document and may be used as reference material or cited as a normative reference
from another document. W3C’s role in making the Recommendation is to
draw attention to the specification and to promote its widespread deployment.
This enhances the functionality and interoperability of the Web.
The canvas
For all media, the term canvas describes "the space where the formatting structure
is rendered." The canvas is infinite for each dimension of the space, but
rendering generally occurs within a finite region of the canvas, established by the
user agent according to the target medium. For instance, user agents rendering
to a screen generally impose a minimum width and choose an initial width based
on the dimensions of the viewport [p. 96] . User agents rendering to a page
generally impose width and height constraints. Aural user agents may impose
limits in audio space, but not in time.
Definitions
In this section, we begin the formal specification of CSS2, starting with the
contract between authors, users, and implementers.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119 (see [RFC2119]).
However, for readability, these words do not appear in all uppercase letters in
this specification.
At times, this specification recommends good practice for authors and user
agents. These recommendations are not normative and conformance with this
specification does not depend on their realization. These recommendations
contain the expression "We recommend ...", "This specification recommends ...",
or some similar wording.