CSS Cascading and Inheritance Level 4

W3C First Public Working Draft,

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www-style@w3.org with subject line “[css-cascade] … message topic …” (archives)
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fantasai (Mozilla)
Tab Atkins Jr. (Google)


This CSS module describes how to collate style rules and assign values to all properties on all elements. By way of cascading and inheritance, values are propagated for all properties on all elements.

New in this level are the default keyword and <supports-condition> for the @import rule.

CSS is a language for describing the rendering of structured documents (such as HTML and XML) on screen, on paper, in speech, etc.

Status of this document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Publication as a First Public Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

The (archived) public mailing list www-style@w3.org (see instructions) is preferred for discussion of this specification. When sending e-mail, please put the text “css-cascade” in the subject, preferably like this: “[css-cascade] …summary of comment…

This document was produced by the CSS Working Group (part of the Style Activity).

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 August 2014 W3C Process Document.

Table of Contents

1. Introduction

One of the fundamental design principles of CSS is cascading, which allows several style sheets to influence the presentation of a document. When different declarations try to set a value for the same element/property combination, the conflicts must somehow be resolved.

The opposite problem arises when no declarations try to set a the value for an element/property combination. In this case, a value is be found by way of inheritance or by looking at the property’s initial value.

The cascading and defaulting process takes a set of declarations as input, and outputs a specified value for each property on each element.

The rules for finding the specified value for all properties on all elements in the document are described in this specification. The rules for finding the specified values in the page context and its margin boxes are described in [CSS3PAGE].

2. Importing Style Sheets: the @import rule

The @import rule allows users to import style rules from other style sheets. If an @import rule refers to a valid stylesheet, user agents must treat the contents of the stylesheet as if they were written in place of the @import rule.

For example, declarations in style rules from imported stylesheets interact with the cascade as if they were written literally into the stylesheet at the point of the @import. Similarly, style rules in a stylesheet imported into a scoped stylesheet are scoped in the same way.

Any @import rules must precede all other at-rules and style rules in a style sheet (besides @charset, which must be the first thing in the style sheet if it exists), or else the @import rule is invalid. The syntax of @import is:

@import [ <url> | <string> ] [ supports( <supports-condition> ) ]? <media-query-list>? ;

Where the <url> or <string> gives the URL of the style sheet to be imported, and the optional <supports-condition> and <media-query-list> (collectively, the import conditions) state the conditions under which it applies.

Syntax for incorporating <supports-condition> is currently under discussion; suggestions and feedback welcome!

If a <string> is provided, it must be interpreted as a <url> with the same value.

The following lines are equivalent in meaning and illustrate both @import syntaxes (one with url() and one with a bare string):
@import "mystyle.css";
@import url("mystyle.css");

The import conditions allow the import to be media– or feature-support–dependent. In the absence of any import conditions, the import is unconditional. (Specifying all for the <media-query-list> has the same effect.)

The evaluation and full syntax of the import conditions is defined by the Media Queries [MEDIAQ] and CSS Conditional Rules [CSS3-CONDITIONAL] specifications. If the conditions do not match, the rules in the imported stylesheet do not apply, exactly as if the imported stylesheet were wrapped in @media and/or @supports blocks with the given conditions.

The following rules illustrate how @import rules can be made media-dependent:
@import url("fineprint.css") print;
@import url("bluish.css") projection, tv;
@import url("narrow.css") handheld and (max-width: 400px);

User agents may therefore avoid fetching a conditional import as long as the import conditions do not match. Additionally, if a <supports-condition> blocks the application of the imported style sheet, the UA must not fetch the style sheet (unless it is loaded through some other link) and must return null for the import rule’s CSSImportRule.styleSheet value (even if it is loaded through some other link).

The following rule illustrates how an author can provide fallback rules for legacy user agents without impacting network performance on newer user agents:
@import url("fallback-layout.css") supports(not (display: flex));
@supports (display: flex) {

When the same style sheet is imported or linked to a document in multiple places, user agents must process (or act as though they do) each link as though the link were to an independent style sheet.

Note: This does not place any requirements on resource fetching, only how the style sheet is reflected in the CSSOM and used in specs such as this one. Assuming appropriate caching, it is perfectly appropriate for a UA to fetch a style sheet only once, even though it’s linked or imported multiple times.

The origin of an imported style sheet is the origin of the style sheet that imported it.

The environment encoding of an imported style sheet is the encoding of the style sheet that imported it. [CSS3SYN]

2.1. Content-Type of CSS Style Sheets

The processing of imported style sheets depends on the actual type of the linked resource. If the resource does not have Content-Type metadata, or the host document is in quirks mode and has the same origin as the imported style sheet, the type of the linked resource is text/css. Otherwise, the type is determined from its Content-Type metadata.

If the linked resource’s type is text/css, it must be interpreted as a CSS style sheet. Otherwise, it must be interpreted as a network error.

3. Shorthand Properties

Some properties are shorthand properties, meaning that they allow authors to specify the values of several properties with a single property. A shorthand property sets all of its longhand sub-properties, exactly as if expanded in place.

When values are omitted from a shorthand form, unless otherwise defined, each “missing” sub-property is assigned its initial value.

This means that a shorthand property declaration always sets all of its sub-properties, even those that are not explicitly set. Carelessly used, this might result in inadvertently resetting some sub-properties. Carefully used, a shorthand can guarantee a “blank slate” by resetting sub-properties inadvertently cascaded from other sources.

For example, writing background: green rather than background-color: green ensures that the background color overrides any earlier declarations that might have set the background to an image with background-image.

For example, the CSS Level 1 font property is a shorthand property for setting font-style, font-variant, font-weight, font-size, line-height, and font-family all at once. The multiple declarations of this example:
h1 {
  font-weight: bold;
  font-size: 12pt;
  line-height: 14pt;
  font-family: Helvetica;
  font-variant: normal;
  font-style: normal;

can therefore be rewritten as

h1 { font: bold 12pt/14pt Helvetica }

As more font sub-properties are introduced into CSS, the shorthand declaration resets those to their initial values as well.

In some cases, a shorthand might have different syntax or special keywords that don’t directly correspond to values of its sub-properties. (In such cases, the shorthand will explicitly define the expansion of its values.)

In other cases, a property might be a reset-only sub-property of the shorthand: Like other sub-properties, it is reset to its initial value by the shorthand when unspecified, but the shorthand might not include syntax to set the sub-property to any of its other values. For example, the border shorthand resets border-image to its initial value of none, but has no syntax to set it to anything else. [CSS3BG]

If a shorthand is specified as one of the CSS-wide keywords [CSS3VAL], it sets all of its sub-properties to that keyword, including any that are reset-only sub-properties. (Note that these keywords cannot be combined with other values in a single declaration, not even in a shorthand.)

Declaring a shorthand property to be !important is equivalent to declaring all of its sub-properties to be !important.

3.1. Resetting All Properties: the all property

Name: all
Value: initial | inherit | unset
Initial: See individual properties
Applies to: See individual properties
Inherited: See individual properties
Percentages: See individual properties
Media: See individual properties
Computed value: See individual properties
Animatable: See individual properties

The all property is a shorthand that resets all CSS properties except direction and unicode-bidi. It only accepts the CSS-wide keywords.

Note: The excepted properties are actually markup-level features, and should not be set in the author’s style sheet. (They exist as CSS properties only to style document languages not supported by the UA.) Authors should use the appropriate markup, such as HTML’s dir attribute, instead. [CSS3-WRITING-MODES]

For example, if an author specifies all: initial on an element it will block all inheritance and reset all properties, as if no rules appeared in the author, user, or user-agent levels of the cascade.

This can be useful for the root element of a "widget" included in a page, which does not wish to inherit the styles of the outer page. Note, however, that any "default" style applied to that element (such as, e.g. display: block from the UA style sheet on block elements such as <div>) will also be blown away.

4. Value Processing

Once a user agent has parsed a document and constructed a document tree, it must assign, to every element in the tree, and correspondingly to every box in the formatting structure, a value to every property that applies to the target media type.

The final value of a CSS property for a given element or box is the result of a multi-step calculation:

4.1. Declared Values

Each property declaration applied to an element contributes a declared value for that property associated with the element. See Filtering Declarations for details.

These values are then processed by the cascade to choose a single “winning value”.

4.2. Cascaded Values

The cascaded value represents the result of the cascade: it is the declared value that wins the cascade (is sorted first in the output of the cascade). If the output of the cascade is an empty list, there is no cascaded value.

4.3. Specified Values

The specified value the value of a given property that the style sheet authors intended for that element. It is the result of putting the cascaded value through the defaulting processes, guaranteeing that a specified value exists for every property on every element.

In many cases, the specified value is the cascaded value. However, if there is no cascaded value at all, the specified value is defaulted. The initial and inherit keywords are handled specially when they are the cascaded value of a property,

4.4. Computed Values

The computed value is the result of resolving the specified value as defined in the “Computed Value” line of the property definition table, generally absolutizing it in preparation for inheritance.

Note: The computed value is the value that is transferred from parent to child during inheritance. For historical reasons, it is not necessarily the value returned by the getComputedStyle() function.

A specified value can be either absolute (i.e., not relative to another value, as in red or 2mm) or relative (i.e., relative to another value, as in auto, 2em). Computing a relative value generally absolutizes it:

See examples (f), (g) and (h) in the table below.

Note: In general, the computed value resolves the specified value as far as possible without laying out the document or performing other expensive or hard-to-parallelize operations, such as resolving network requests or retrieving values other than from the element and its parent.

The computed value exists even when the property does not apply (as defined by the “Applies To” line). However, some properties may change how they determine the computed value based on whether the property applies to the element.

4.5. Used Values

The used value is the result of taking the computed value and completing any remaining calculations to make it the absolute theoretical value used in the layout of the document. If the property does not apply to this element, then the element has no used value for that property.

For example, a declaration of width: auto can’t be resolved into a length without knowing the layout of the element’s ancestors, so the computed value is auto, while the used value is an absolute length, such as 100px. [CSS21]

As another example, a <div> might have a computed break-before value of auto, but acquire a used break-before value of page by propagation from its first child. [CSS3-BREAK]

Lastly, if a property does not apply to an element, it has no used value; so, for example, the flex property has no used value on elements that aren’t flex items.

4.6. Actual Values

A used value is in principle ready to be used, but a user agent may not be able to make use of the value in a given environment. For example, a user agent may only be able to render borders with integer pixel widths and may therefore have to approximate the used width. Also, the font size of an element may need adjustment based on the availability of fonts or the value of the font-size-adjust property. The actual value is the used value after any such adjustments have been made.

Note: By probing the actual values of elements, much can be learned about how the document is laid out. However, not all information is recorded in the actual values. For example, the actual value of the page-break-after property does not reflect whether there is a page break or not after the element. Similarly, the actual value of orphans does not reflect how many orphan lines there is in a certain element. See examples (j) and (k) in the table below.

4.7. Examples

Property Winning declaration Cascaded value Specified value Computed value Used value Actual value
(a) text-align text-align: left left left left left left
(b) border-top-width, border-right-width, border-bottom-width, border-left-width border-width: inherit inherit 4.2px 4.2px 4.2px 4px
(c) width (none) (none) auto (initial value) auto 120px 120px
(d) list-style-position list-style-position: inherit inherit inside inside inside inside
(e) list-style-position list-style-position: initial initial outside (initial value) outside outside outside
(f) font-size font-size: 1.2em 1.2em 1.2em 14.1px 14.1px 14px
(g) width width: 80% 80% 80% 80% 354.2px 354px
(h) width width: auto auto auto auto 134px 134px
(i) height height: auto auto auto auto 176px 176px
(j) page-break-after (none) (none) auto (initial value) auto auto auto
(k) orphans orphans: 3 3 3 3 3 3

5. Filtering

In order to find the declared values, implementations must first identify all declarations that apply to each element. A declaration applies to an element if:

The values of the declarations that apply form, for each property on each element, a list of declared values. The next section, the cascade, prioritizes these lists.

6. Cascading

The cascade takes a unordered list of declared values for a given property on a given element, sorts them by their declaration’s precedence as determined below, and outputs a single cascaded value.

The cascade sorts declarations according to the following criteria, in descending order of priority:

Origin and Importance
The origin of a declaration is based on where it comes from and its importance is whether or not it is declared !important (see below). The precedence of the various origins is, in descending order:
  1. Transition declarations [CSS3-TRANSITIONS]
  2. Important user agent declarations
  3. Important user declarations
  4. Important override declarations [DOM-LEVEL-2-STYLE]
  5. Important author declarations
  6. Animation declarations [CSS3-ANIMATIONS]
  7. Normal override declarations [DOM-LEVEL-2-STYLE]
  8. Normal author declarations
  9. Normal user declarations
  10. Normal user agent declarations

Declarations from origins earlier in this list win over declarations from later origins.

A declaration can be scoped to a subtree of the document so that it only affects its scoping element and that element’s descendants. For example, [HTML5] defines scoped <style> elements, whose style sheets are scoped to the element’s parent.

If the scoping elements of two declarations have an ancestor/descendant relationship, then for normal rules the declaration whose scoping element is the descendant wins, and for important rules the declaration whose scoping element is the ancestor wins.

Note: In other words, for normal declarations the inner scope’s declarations override, but for !important rules outer scope’s override.

For the purpose of this step, all unscoped declarations are considered to be scoped to the root element. Normal declarations from style attributes are considered to be scoped to the element with the attribute, whereas important declarations from style attributes are considered to be scoped to the root element. [CSSSTYLEATTR]

Note: This odd handling of !important style attribute declarations is to match the behavior defined in CSS Levels 1 and 2, where style attributes simply have higher specificity than any other author rules. [CSS21]

The Selectors module [SELECT] describes how to compute the specificity of a selector. Each declaration has the same specificity as the style rule it appears in. For the purpose of this step, declarations that do not belong to a style rule (such as the contents of a style attribute) are considered to have a specificity higher than any selector. The declaration with the highest specificity wins.
Order of Appearance
The last declaration in document order wins. For this purpose:
  • Declarations from imported style sheets are ordered as if their style sheets were substituted in place of the @import rule.
  • Declarations from style sheets independently linked by the originating document are treated as if they were concatenated in linking order, as determined by the host document language.
  • Declarations from style attributes are ordered according to the document order of the element the style attribute appears on, and are all placed after any style sheets.

The output of the cascade is a (potentially empty) sorted list of declared values for each property on each element.

6.1. Cascading Origins

Each style rule has an origin, which determines where it enters the cascade. CSS defines three core origins:

The author specifies style sheets for a source document according to the conventions of the document language. For instance, in HTML, style sheets may be included in the document or linked externally.
The user may be able to specify style information for a particular document. For example, the user may specify a file that contains a style sheet or the user agent may provide an interface that generates a user style sheet (or behaves as if it did).
User agent
Conforming user agents must apply a default style sheet (or behave as if they did). A user agent’s default style sheet should present the elements of the document language in ways that satisfy general presentation expectations for the document language (e.g., for visual browsers, the EM element in HTML is presented using an italic font). See e.g. the HTML user agent style sheet. [HTML5]

Extensions to CSS define the following additional origins:

DOM Level 2 Style [DOM-LEVEL-2-STYLE] defines an interface for “override” styles, which enter the cascade at a higher level than other author rules.
CSS Animations [CSS3-ANIMATIONS] generate “virtual” rules representing their effects when running.
Like CSS Animations, CSS Transitions [CSS3-TRANSITIONS] generate “virtual” rules representing their effects when running.

6.2. Important Declarations: the !important annotation

CSS attempts to create a balance of power between author and user style sheets. By default, rules in an author’s style sheet override those in a user’s style sheet, which override those in the user-agent’s default style sheet. To balance this, a declaration can be made important, which increases its weight in the cascade and inverts the order of precedence.

A declaration is important if it has a !important annotation, as defined by [CSS3SYN]. i.e. if the last two (non-whitespace, non-comment) tokens in its value are the delimiter token ! followed by the identifier token important.

[hidden] { display: none !important; }

An important declaration takes precedence over a normal declaration. Author and user style sheets may contain !important declarations, with user !important declarations overriding author !important declarations. This CSS feature improves accessibility of documents by giving users with special requirements (large fonts, color combinations, etc.) control over presentation.

Important declarations from all origins take precedence over animations. This allows authors to override animated values in important cases. (Animated values normally override all other rules.) [CSS3-ANIMATIONS]

User agent style sheets may also contain !important declarations. These override all author and user declarations.

The first rule in the user’s style sheet in the following example contains an !important declaration, which overrides the corresponding declaration in the author’s style sheet. The declaration in the second rule will also win due to being marked !important. However, the third declaration in the user’s style sheet is not !important and will therefore lose to the second rule in the author’s style sheet (which happens to set style on a shorthand property). Also, the third author rule will lose to the second author rule since the second declaration is !important. This shows that !important declarations have a function also within author style sheets.
/* From the user’s style sheet */
p { text-indent: 1em !important }
p { font-style: italic !important }
p { font-size: 18pt }

/* From the author’s style sheet */
p { text-indent: 1.5em !important }
p { font: normal 12pt sans-serif !important }
p { font-size: 24pt }

6.3. Precedence of Non-CSS Presentational Hints

The UA may choose to honor presentational hints in a source document’s markup, for example the bgcolor attribute or <s> element in [HTML5]. All document language-based styling must be translated to corresponding CSS rules and either enter the cascade at the user agent level or be treated as author level rules with a specificity of zero placed at the start of the author style sheet. A document language may define whether a presentational hint enters at the UA or author level of the cascade; if so, the UA must behave accordingly. For example, [SVG11] maps its presentation attributes into the author level.

Note: Presentational hints entering the cascade at the UA level can be overridden by author or user styles. Presentational hints entering the cascade at the author level can be overridden by author styles, but not by non-!important user styles. Host languages should choose the appropriate level for presentational hints with these considerations in mind.

7. Defaulting

When the cascade does not result in a value, the specified value must be found some other way. Inherited properties draw their defaults from their parent element through inheritance; all other properties take their initial value. Authors can explicitly request inheritance or initialization via the inherit and initial keywords.

7.1. Initial Values

Each property has an initial value, defined in the property’s definition table. If the property is not an inherited property, and the cascade does not result in a value, then the specified value of the property is its initial value.

7.2. Inheritance

Inheritance propagates property values from parent elements to their children. The inherited value of a property on an element is the computed value of the property on the element’s parent element. For the root element, which has no parent element, the inherited value is the initial value of the property.

(Pseudo-elements inherit according to a fictional tag sequence described for each pseudo-element [SELECT].)

Some properties are inherited properties, as defined in their property definition table. This means that, unless the cascade results in a value, the value will be determined by inheritance.

A property can also be explicitly inherited. See the inherit keyword.

Note: Inheritance follows the document tree and is not intercepted by anonymous boxes, or otherwise affected by manipulations of the box tree.

7.3. Explicit Defaulting

Several CSS-wide property values are defined below; declaring a property to have these values explicitly specifies a particular defaulting behavior. As specified in CSS Values and Units Level 3 [CSS3VAL], all CSS properties can accept these values.

7.3.1. Resetting a Property: the initial keyword

If the cascaded value of a property is the initial keyword, the property’s initial value becomes its specified value.

7.3.2. Explicit Inheritance: the inherit keyword

If the cascaded value of a property is the inherit keyword, the inherited value becomes the property’s specified and computed values.

7.3.3. Erasing All Declarations: the unset keyword

If the cascaded value of a property is the unset keyword, then if it is an inherited property, this is treated as inherit, and if it is not, this is treated as initial. This keyword effectively erases all declared values occurring earlier in the cascade, correctly inheriting or not as appropriate for the property (or all longhands of a shorthand).

7.3.4. Rolling Back The Cascade: the default keyword

If the cascaded value of a property is the default keyword, the behavior depends on the origin to which the declaration belongs:

user-agent origin
Equivalent to unset.
user origin
Rolls back the cascade to the user-agent level, so that the specified value is calculated as if no author-level or user-level rules were specified for this property.
author origin
Rolls back the cascade to the user level, so that the specified value is calculated as if no author-level rules were specified for this property. For the purpose of default, this origin includes the Override and Animation origins.

8. Changes

8.1. Additions Since Level 3

The following additions were made to this specification since the Level 3 CR:


David Baron, Simon Sapin, and Boris Zbarsky contributed to this specification.


Document conventions

Conformance requirements are expressed with a combination 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 the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words "for example" or are set apart from the normative text with class="example", like this:

This is an example of an informative example.

Informative notes begin with the word "Note" and are set apart from the normative text with class="note", like this:

Note, this is an informative note.

Advisements are normative sections styled to evoke special attention and are set apart from other normative text with <strong class="advisement">, like this: UAs MUST provide an accessible alternative.

Conformance classes

Conformance to this specification is defined for three conformance classes:

style sheet
A CSS style sheet.
A UA that interprets the semantics of a style sheet and renders documents that use them.
authoring tool
A UA that writes a style sheet.

A style sheet is conformant to this specification if all of its statements that use syntax defined in this module are valid according to the generic CSS grammar and the individual grammars of each feature defined in this module.

A renderer is conformant to this specification if, in addition to interpreting the style sheet as defined by the appropriate specifications, it supports all the features defined by this specification by parsing them correctly and rendering the document accordingly. However, the inability of a UA to correctly render a document due to limitations of the device does not make the UA non-conformant. (For example, a UA is not required to render color on a monochrome monitor.)

An authoring tool is conformant to this specification if it writes style sheets that are syntactically correct according to the generic CSS grammar and the individual grammars of each feature in this module, and meet all other conformance requirements of style sheets as described in this module.

Partial implementations

So that authors can exploit the forward-compatible parsing rules to assign fallback values, CSS renderers must treat as invalid (and ignore as appropriate) any at-rules, properties, property values, keywords, and other syntactic constructs for which they have no usable level of support. In particular, user agents must not selectively ignore unsupported component values and honor supported values in a single multi-value property declaration: if any value is considered invalid (as unsupported values must be), CSS requires that the entire declaration be ignored.

Experimental implementations

To avoid clashes with future CSS features, the CSS2.1 specification reserves a prefixed syntax for proprietary and experimental extensions to CSS.

Prior to a specification reaching the Candidate Recommendation stage in the W3C process, all implementations of a CSS feature are considered experimental. The CSS Working Group recommends that implementations use a vendor-prefixed syntax for such features, including those in W3C Working Drafts. This avoids incompatibilities with future changes in the draft.

Non-experimental implementations

Once a specification reaches the Candidate Recommendation stage, non-experimental implementations are possible, and implementors should release an unprefixed implementation of any CR-level feature they can demonstrate to be correctly implemented according to spec.

To establish and maintain the interoperability of CSS across implementations, the CSS Working Group requests that non-experimental CSS renderers submit an implementation report (and, if necessary, the testcases used for that implementation report) to the W3C before releasing an unprefixed implementation of any CSS features. Testcases submitted to W3C are subject to review and correction by the CSS Working Group.

Further information on submitting testcases and implementation reports can be found from on the CSS Working Group’s website at http://www.w3.org/Style/CSS/Test/. Questions should be directed to the public-css-testsuite@w3.org mailing list.


Terms defined by this specification

Terms defined by reference


Normative References

Bert Bos; et al. Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification. 7 June 2011. W3C Recommendation. URL: http://www.w3.org/TR/2011/REC-CSS2-20110607
Håkon Wium Lie; Tab Atkins; Elika J. Etemad. CSS Values and Units Module Level 3. 30 July 2013. W3C Candidate Recommendation. (Work in progress.) URL: http://www.w3.org/TR/2013/CR-css3-values-20130730/
Tantek Çelik; Elika J. Etemad. CSS Style Attributes. 12 October 2010. W3C Candidate Recommendation. (Work in progress.) URL: http://www.w3.org/TR/2010/CR-css-style-attr-20101012/
Chris Wilson; Philippe Le Hégaret. Document Object Model (DOM) Level 2 Style Specification. 13 November 2000. REC. URL: http://www.w3.org/TR/DOM-Level-2-Style/
Florian Rivoal. Media Queries. 19 June 2012. W3C Recommendation. URL: http://www.w3.org/TR/2012/REC-css3-mediaqueries-20120619/
Tantek Çelik; et al. Selectors Level 3. 29 September 2011. W3C Recommendation. URL: http://www.w3.org/TR/2011/REC-css3-selectors-20110929/
CSS Backgrounds and Borders Module Level 3 URL: http://www.w3.org/TR/css3-background/
CSS Fragmentation Module Level 3 URL: http://www.w3.org/TR/css3-break/
CSS Conditional Rules Module Level 3 URL: http://www.w3.org/TR/css3-conditional/
Tab Atkins Jr.; Elika Etemad; Rossen Atanassov. CSS Flexible Box Layout Module Level 1. 25 September 2014. LCWD. URL: http://www.w3.org/TR/css-flexbox-1/
John Daggett. CSS Fonts Module Level 3. 3 October 2013. CR. URL: http://www.w3.org/TR/css-fonts-3/
Tab Atkins Jr.. CSS Lists and Counters Module Level 3. 20 March 2014. WD. URL: http://www.w3.org/TR/css-lists-3/
Tab Atkins Jr.; Simon Sapin. CSS Syntax Module Level 3. 20 February 2014. CR. URL: http://www.w3.org/TR/css-syntax-3/
Elika Etemad; Koji Ishii. CSS Text Module Level 3. 10 October 2013. LCWD. URL: http://www.w3.org/TR/css-text-3/
CSS Values and Units Module Level 3 URL: http://www.w3.org/TR/css3-values/
Elika Etemad; Koji Ishii. CSS Writing Modes Level 3. 20 March 2014. CR. URL: http://www.w3.org/TR/css-writing-modes-3/
Dean Jackson; et al. CSS Animations. 19 February 2013. WD. URL: http://www.w3.org/TR/css3-animations/
David Baron. CSS Conditional Rules Module Level 3. 4 April 2013. CR. URL: http://www.w3.org/TR/css3-conditional/
Dean Jackson; et al. CSS Transitions. 19 November 2013. WD. URL: http://www.w3.org/TR/css3-transitions/
Florian Rivoal; Tab Atkins Jr.. Media Queries Level 4. 5 June 2014. WD. URL: http://www.w3.org/TR/mediaqueries-4/
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: http://www.ietf.org/rfc/rfc2119.txt

Informative References

Elika J. Etemad; Koji Ishii. CSS Writing Modes Module Level 3. 15 November 2012. W3C Working Draft. (Work in progress.) URL: http://www.w3.org/TR/2012/WD-css3-writing-modes-20121115/
Bert Bos; Elika J. Etemad; Brad Kemper. CSS Backgrounds and Borders Module Level 3. 24 July 2012. W3C Candidate Recommendation. (Work in progress.) URL: http://www.w3.org/TR/2012/CR-css3-background-20120724/
Melinda Grant; et al. CSS Paged Media Module Level 3. 14 March 2013. W3C Working Draft. (Work in progress.) URL: http://www.w3.org/TR/2013/WD-css3-page-20130314/
Tab Atkins Jr.; Simon Sapin. CSS Syntax Module. 5 November 2013. W3C Working Draft. (Work in progress.) URL: http://www.w3.org/TR/2013/WD-css-syntax-3-20131105/
Erik Dahlström; et al. Scalable Vector Graphics (SVG) 1.1 (Second Edition). 16 August 2011. REC. URL: http://www.w3.org/TR/SVG11/
Rossen Atanassov; Elika Etemad. CSS Fragmentation Module Level 3. 16 January 2014. WD. URL: http://www.w3.org/TR/css3-break/
Robin Berjon; et al. HTML5. 28 October 2014. REC. URL: http://www.w3.org/TR/html5/

Property Index

Name Value Initial Applies to Inh. %ages Media Animatable Computed value
all initial | inherit | unset See individual properties See individual properties See individual properties See individual properties See individual properties See individual properties See individual properties

Issues Index

Syntax for incorporating <supports-condition> is currently under discussion; suggestions and feedback welcome!