This specification defines in general a subset of CSS 2.1 [CSS21] that is to be considered a baseline for interoperability between implementations of CSS on constrained devices (e.g. mobile phones). Its intent is not to produce a profile of CSS incompatible with the complete specification, but rather to ensure that implementations that due to platform limitations cannot support the entire specification implement a common subset that is interoperable not only amongst constrained implementations but also with complete ones. Additionally, this specification aligns itself as much as possible with the OMA's Wireless CSS 1.1 [WCSS11] specification.
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This document was produced by the CSS Working Group (part of the Style Activity).
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This document specifies a profile of CSS that is a subset of CSS 2.1 [CSS21].
The key words of descriptive assertions and RFC 2119 terminology. 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 [RFC2119].
Since the goal of this specification is to define a baseline interoperability level, user agents MAY accept CSS documents conforming to CSS 2.1 or subsequent revisions of the CSS family of Recommendations.
In order to conform to this specification, user agents, authoring tools, and content MUST conform to the Conformance and Error conditions section of the CSS 2.1 specification [CSS21], with the following modifications.
allmedia types MUST be accepted and processed. Other media types MAY be accepted and processed as well.
Selectors are defined in the Selectors chapter of the CSS 2.1 specification [CSS21]. The following table identifies which selector constructs MUST be supported amongst those defined by CSS 2.1.
|Universal selector||Matches any element.|
|Type selectors||Matches any E element.|
|Descendant selectors||Matches any F element that is a descendant of an E element.|
|Child selectors||Matches any F element that is a child of an element E.|
|The link pseudo-classes||Matches element E if E is the source anchor of a hyperlink, unvisited by a user.|
|The link pseudo-classes||Matches element E if E is the source anchor of a hyperlink, visited by a user.|
|The dynamic pseudo-classes||Matches element E if E is being activated by the user.|
|The dynamic pseudo-classes||Matches element E if E has the focus (accepts keyboard events or other forms of text input).|
|Class selectors|| Language specific. (In (X)HTML, matches elements whose
|ID selectors||Matches any element with an ID equal to "myid".|
|Grouping||Matches a group of elements, which share the same style declarations.|
Should Namespace selectors (a CSS level 3 feature, see [SELECT]) also be required?
At-rules are defined in the At-rules section of the CSS 2.1 specification [CSS21]. The following table identifies which at-rule constructs MUST be supported amongst those defined by CSS 2.1.
|@charset||Defines character set for the style sheet.|
|@import||Imports an external style sheet.|
|@media||Groups a set of style rules to apply only to one or more particular media.|
Properties are defined in the in several chapters of the CSS 2.1 specification [CSS21]. The following table identifies which properties MUST be supported amongst those defined by CSS 2.1, as well as their syntax (expressed using the same value specifications as CSS 2.1) when it is subsetted from the original.
Limitations that apply to a property apply equally to its shorthand alternative.
|Property||Syntax (if different from CSS 2.1)|
'Input'. These extensions are not part of this specification.
A user agent MUST support all value types defined in the Values section of the CSS 2.1 specification [CSS21], with the following exceptions:
The editors wish to thank the authors of the previous version of this document, Ted Wugofski (Openwave), Doug Dominiak (Openwave,formerly Motorola), Peter Stark (Ericsson), and Tapas Roy (Openwave), as well as the authors of the OMA Wireless CSS specification and the CSS 2.1 specification. Furthermore, the editors want to thank the CDF WG for their participation on this specification.