Copyright © 2004 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.
This section is informative.
CSS (Cascading Style Sheets) is a language for describing the rendering of HTML and XML documents on screen, on paper, in speech, etc. It uses various selectors, properties and values to style basic user interface elements in a document. This specification describes those user interface related selectors, properties and values that are proposed for CSS level 3 to style HTML and XML (including XHTML and XForms). It includes and extends user interface related features from the selectors, properties and values of CSS level 2 revision 1 and Selectors specifications.
This section is normative.
This section describes the status of this document at the time of its publication. Other documents may supersede it. 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/.
This is a W3C Candidate Recommendation, which means the specification has been widely reviewed and W3C recommends that it be implemented. It will remain Candidate Recommendation at least until 11 November 2004.
Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. It is inappropriate to cite this document as other than work in progress.
To find the latest version of this specification, please follow the "Latest version" link above, or visit the list of W3C Technical Reports.
A test suite and a report on implementations will be provided before the document becomes a Proposed Recommendation.
The (archived) public mailing list www-style@w3.org (see instructions) is preferred for discussion of this and other specifications in the Style area. When commenting on this document, please put the text "CSS3UI" in the subject, preferably like this: "[CSS3UI] <summary of comment>"
This document is produced by the CSS Working Group (part of the Style Activity, see summary).
Patent disclosures relevant to CSS may be found on the Working Group's public patent disclosure page. The document was developed under the 24 January 2002 CPP as amended by the W3C Patent Policy Transition Procedure.
For this specification to exit the CR stage, the following conditions must be met:
There must be at least two interoperable implementations for every feature. For the purposes of this criterion, we define the following terms:
A section or subsection of the specification.
passing the respective test cases in the test suite, or, if the implementation is not a web browser, equivalent tests. Every relevant test in the test suite should have an equivalent test created if such a user agent (UA) is to be used to claim interoperability. In addition if such a UA is to be used to claim interoperability, then there must one or more additional UAs which can also pass those equivalent tests in the same way for the purpose of interoperability. The equivalent tests must be made publicly available for the purposes of peer review.
a user agent which:
A minimum of six months of the CR period must have elapsed. This is to ensure that enough time is given for any remaining major errors to be caught.
The CR period will be extended if implementations are slow to appear.
Features that are at risk (see the below list) will be dropped (thus reducing the list of "all" features mentioned above) if two or more interoperable implementations of those features are not found by the end of the CR period, or if sufficient and adequate tests (by judgment of the Working Group) have not been produced for those features by the end of the CR period.
The Working Group has identified the following features as at risk of being removed from CSS3 Basic User Interface when exiting CR. Implementors are urged to implement these features, if they wish to see these features remain in this specification. All other features are either defined in a normative reference (e.g. CSS 2.1 [CSS21] or Selectors [SELECT]), or dependencies for another specification (e.g. XForms [XFORMS10]) or are believed to have one or more implementations (perhaps experimental), and thus will not be dropped without returning to last call.
This section is informative.
This document is one of the "modules" for the upcoming CSS3 specification. It not only describes the user interface related properties and values that already exist in CSS1 [CSS1] and CSS2.1 [CSS21], but introduces new properties and values for CSS3 as well. The Working Group doesn't expect that all implementations of CSS3 will implement all properties or values. Instead, there will probably be a small number of variants of CSS3, so-called "profiles".
This document is the result of the merging of relevant parts of the following Recommendations and Working Drafts, and the addition of some new features.
This specification contains:
This section is normative.
CSS3 is a set of modules, divided up and profiled in order to simplify the specification, and to allow implementors the flexibility of supporting the particular modules appropriate for their implementations.
This module describes selectors and CSS properties which enable authors to style user interface related states, element fragments, properties and values.
Section 2.1 of CSS1 [CSS1] and Chapter 18 of CSS2 [CSS2] introduced several user interface related pseudo-classes, properties and values. Section 6.6.4 of Selectors [SELECT] also describes several additional user interface related pseudo-classes (and one pseudo-element).
This Working Draft extends them to provide the ability, through CSS, to style elements based upon additional user interface states, to style fragments of user interface elements, and to alter the dynamic presentation of elements in ways previously only available through specific HTML4/XHTML1 elements and attributes.
The purpose of this specification is to achieve the following objectives:
This proposal specifies how to alter the look and feel of various elements, and specifically does not address the meaning behind what a specific look and feel may imply. For example, with the additions in the proposal, an author can make any element look and even feel like a submit button. Yet, that arbitrary element is not afforded any additional meaning, so pushing it does nothing by default, and certainly does not submit a form.
Similarly, the HTML4 <SELECT> element for example,
provides a list or menu of choices to the user. The meaning of the HTML4
<SELECT> element is that it allows the user to make a
choice, to choose something among several alternatives. This says nothing
about its look and feel, and in fact, the "concept" of a HTML4
<SELECT> could be visually implemented as a list-box, a
popup-menu, or a group of radio-buttons. Or a group of HTML4 checkboxes
(<INPUT type="checkbox">) could be styled to appear as a
group of radio-buttons, and yet, since those elements are still semantic
checkboxes, they can still be individually checked or unchecked, rather than
acquiring any kind of radio-button group semantic where only one can be
checked.
Each example of presentation has a different look and feel, but maintains its original meaning, a choice (or choices) among several alternatives. This proposal addresses only the former (look and feel), not the latter (meaning).
Since this proposal serves to simulate the appearance of various user interface and forms elements in HTML4/XHTML, it is perhaps useful to call out what specifically is believed to be outside the scope of CSS, or better suited to document structure rather than style and therefore not addressed by this proposal:
maxlength' attribute,
for example, determines the maximum number of characters the user can enter
into an <INPUT type="text"> or <INPUT
type="password"> field, and as such is a content constraint rather
than a presentational suggestion.
<form> element and its unique
attributes ('action', 'method',
'enctype', 'accept',
'accept-charset').
In addition, this document does not attempt to solve all user interface related issues / features that can be found in modern user interfaces. Perhaps future versions may attempt to solve these. For example:
<INPUT
type="file"> and the <ISINDEX> elements).
<fieldset>,
<legend>, <frame> and
<frameset> elements.
<frame> and
<frameset>, specifically the ability to "share"
resizability when elements share a border, perhaps by leveraging the
border-collapse property is also not addressed.
This section is normative.
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 typically appear in all uppercase letters in this specification.
Additional key words, e.g. "User agent (UA)", are defined by CSS 2.1 ([CSS21], section 3.1).
The following classes of products (many of which overlap) should consider implementing this specification:
This specification contains a number of informative profiles. These profiles are not mandatory for conformance.
This specification does not define any explicit extension mechanisms. If an implementation needs to extend the functionality of this specification, it must follow any/all guidelines and requirements of extensions as defined in CSS2.1, e.g. Vendor-specific extensions ([CSS21], section 4.1.2).
This section is normative.
This CSS3 module depends on the following other specifications. Some of these specifications may be in their "Candidate Recommendation" phase. If this module depends on feature or portion of such a specification which ends up being dropped during their "CR" phase(s), then such feature or portion thereof will be presumed to be incorporated into this specification. For example, if the ":indeterminate" selector was dropped from Selectors, then the definition and description of ":indeterminate" would be incorporated into the next draft of this specification.
The following work is related to the CSS3 Module Basic User Interface Working Draft.
This specification does not define what is a form element.
This section is normative.
The Selectors specification defines several user interface selectors ([SELECT], sections 6.6.1 and 6.6.4) which represent user interface states:
These pseudo-classes as defined by [SELECT] are included in this specification by reference.
CSS 2.1 [CSS21] specifies additional details for some of the selectors mentioned, above and beyond Selectors.
In addition, on systems with more than one mouse button, :active is clarified to apply only to the primary or primary activation button (typically the "left" mouse button), and any aliases thereof.
Authors may wish to completely redo the styling of a form control, such as a checkbox. This can be achieved using several of the above pseudo-classes and the 'normal' value for the 'appearance' property which is explained later in this specification. In this example, checkboxes with a class of "redone" are styled with specific background images according to their respective user interface states using one or more pseudo-classes.
input[type=checkbox] {
appearance:checkbox; /* expected from UA defaults */
}
input[type=checkbox].redone {
appearance:normal; /* resets various properties */
display:inline-block;
width:20px; height:20px;
background:url(customuncheckedimage.png);
}
input[type=checkbox].redone:active {
background:url(customuncheckedactiveimage.png);
}
input[type=checkbox].redone:checked {
background:url(customcheckedimage.png);
}
input[type=checkbox].redone:checked:active {
background:url(customcheckedactiveimage.png);
}
input[type=checkbox].redone:disabled {
background:url(customdisableduncheckedimage.png);
}
input[type=checkbox].redone:disabled:checked {
background:url(customdisabledcheckedimage.png);
}
In addition to the above-mentioned pseudo-classes, this specification introduces several new pseudo-classes to define additional user interface states.
Specifically, these new states (except for :default) are provided as a way to style elements which are in the respective states as defined by XForms [XFORMS10].
The :default selector applies to the one or more UI elements that are the default among a set of similar elements. Typically applies to context menu items, buttons and select lists/menus.
One example is the default submit button among a set of buttons. Another example is the default option from a popup menu. Multiple elements in a select-many group could have multiple :default elements, like a selection of pizza toppings for example.
An element is :valid or :invalid when it is, respectively, valid or invalid with respect to data validity semantics defined by a different specification (e.g. [XFORMS10]). An element which lacks data validity semantics is neither :valid nor :invalid. This is different from an element which otherwise has no constraints. Such an element would always be :valid.
The :in-range and :out-of-range pseudo-classes apply only to elements that have range limitations. An element is :in-range or :out-of-range when the value that the element is bound to is in range or out of range of the presentation (e.g. visual or spoken representation) of the element respectively. An element that lacks data range limits or is not a form control is neither :in-range nor :out-of-range. E.g. a slider element with a value of 11 presented as a slider control that only represents the values from 1-10 is :out-of-range. Another example is a menu element with a value of "E" that happens to be presented as a popup menu that only has choices "A", "B" and "C".
A form element is :required or :optional if a value for it is, respectively, required or optional before the form it belongs to is submitted. Elements that are not form elements are neither required nor optional.
An element whose contents are not user-alterable is :read-only. However, elements whose contents are user-alterable (such as text input fields) are considered to be in a :read-write state. In typical documents, most elements are :read-only. However it may be possible (e.g. in the context of an editor) for any element to become :read-write.
Selectors ([SELECT], section 7.3) also defines one user interface element fragment selector:
This pseudo-element is included in this specification as defined by [SELECT] by reference.
In addition to the above-mentioned pseudo-element, this specification introduces four new pseudo-elements to provide access to additional user interface element fragments.
Specifically, these new pseudo-elements are provided as a way to style user interface fragments as defined by XForms [XFORMS10].
A form element may contain both a label for its data value, and the data value itself. For such elements, the ::value pseudo-element selects the representation of just the data value itself, in order to style its appearance.
Here is an example which illustrates the ::value of a text input field with fictional markup which is then styled with CSS.
<input>
<label>Zip code<label>
<input::value/>
</input>
input { border:dashed }
label { border:dotted }
input::value { border:solid }
Spacing (in the form of padding) has been added to the above approximation to separate the borders and make the individual (pseudo-)elements easier to distinguish.
Similarly, a form element which represents a list of options may contain both a label for the list, and the list of choices itself. For such elements, the ::choices pseudo-element selects the representation of just the list of choices themselves, in order to style their appearance.
A list of radio buttons can also be selected with the ::choices pseudo-element, and the currently chosen radio button can be selected with the ::value pseudo-element.
The ::repeat-item pseudo-element represents a single item from a
repeating sequence. It is generated as a parent to all the elements in a
single repeating item. Each ::repeat-item is associated with a particular
instance data node, and is affected by the model item properties (e.g.
'relevant') found there, as the related style properties will
cascade to the child elements.
The ::repeat-index pseudo-element represents the current item of a repeating sequence. It takes the place of the ::repeat-item as a parent of all the elements in the index repeating item.
Note. Any style declarations that an author wants to apply to all repeat items, including the index, must be done so by using both ::repeat-item and ::repeat-index selectors. Styles that are only applied to ::repeat-item will not automatically be applied to the respective ::repeat-index.
Here is an example that illustrates both ::repeat-item and ::repeat-index, since they are often both available and used at the same time. Assume appropriate namespace declarations were made in a header somewhere preceding the code in the example.
The following markup snippet uses XHTML and XForms:
<html:table xforms:repeat-nodeset="...">
<html:tr>
<html:td><xforms:input ref="..."/><xforms:input ref="..."/></html:td>
</html:tr>
</html:table>
The following style rules are used to style all the repeated items and the current repeated item.
html|tr::repeat-item { outline: medium solid; color:gray }
html|tr::repeat-index { outline: medium dashed; color:black }
The following fictional markup shows the state of the above markup when through user interaction the XForm contains three of the repeated items, where the third item is current.
<html:table xforms:repeat-nodeset="...">
<html:tr::repeat-item>
<html:tr>
<html:td><xforms:input ref="..."/><xforms:input ref="..."/></html:td>
</html:tr>
</html:tr::repeat-item>
<html:tr::repeat-item>
<html:tr>
<html:td><xforms:input ref="..."/><xforms:input ref="..."/></html:td>
</html:tr>
</html:tr::repeat-item>
<html:tr::repeat-index>
<html:tr>
<html:td><xforms:input ref="..."/><xforms:input ref="..."/></html:td>
</html:tr>
</html:tr::repeat-index>
</html:table>
Note. The ::repeat-index pseudo-element takes the place of the ::repeat-item rather than being nested inside as a separate element. Thus just like :link or :visited are mutually exclusive for selecting hyperlinks, only one will exist and apply to a particular repeated item at any point.
The following example from XForms 1.0 ([XFORMS10], section F.3) shows how basic styling can be accomplished on form controls and repeating structures using the new pseudo-classes and XForms elements.
@namespace xforms url(http://www.w3.org/2002/xforms);
/* Display a red background on all invalid form controls */
*:invalid { background-color:red; }
/* Display a red asterisk after all required form controls */
*:required::after { content: "*"; color:red; }
/* Do not render non-relevant form controls */
*:disabled { visibility: hidden; }
/* The following declarations cause form controls and their labels
to align neatly, as if a two-column table were used */
xforms|group { display: table; }
xforms|input { display: table-row; }
xforms|input > xforms|label { display: table-cell; }
xforms|input::value { border: thin black solid; display: table-cell; }
/* Display an alert message when appropriate */
*:valid > xforms|alert { display: none; }
*:invalid > xforms|alert { display: inline; }
/* Display repeat-items with a dashed border */
*::repeat-item,*::repeat-index { border: dashed; }
/* Display a teal highlight behind the current repeat item */
*::repeat-index { background-color: teal; }
This section is normative.
CSS2 introduced the concept of system colors, which is a set of keywords that allows authors to specify colors in a manner that integrates them into the user's graphic environment. However, color is not the only property for which native form controls have a default.
The properties defined and extended in this section refer to the <appearance> value type, which may take one of the following values which have been derived from the list of CSS2.1 System Colors ([CSS21], section 18.2), the list of HTML4 form controls ([HTML401], section 17), and additional typical platform user interface (UI) controls (e.g. dialog window, icon):
Conforming user agents must support the five generic appearance values: 'icon', 'window', 'button', 'menu' and 'field'. If a user agent or platform does not support a specific user interface element (e.g. 'dialog'), it may apply the values for the respective generic user interface element (e.g. 'window').
Note. This specification recommends that user agents allow users to override system appearance and font selections with their own choices or proportions, within the user agent. See the User Agent Accessibility Guidelines, specifically Ensure user control of rendering ([UAAG10], section 2 guideline 4).
| Name: | appearance |
| Value: | normal | <appearance> | inherit |
| Initial: | normal |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual, interactive |
| Computed value: | specified value |
This document introduces the 'appearance' property which can be used to make an element look like a standard user interface element on the platform.
| 'appearance' | HTML4 demonstration |
|---|---|
| normal | hello |
| button | |
| push-button | |
| hyperlink | CSS home page |
| radio-button | |
| checkbox | |
| pop-up-menu | |
| list-menu | |
| radio-group | |
| checkbox-group | |
| field | |
| password |
The 'appearance' property is a shorthand for 'appearance', 'color', 'font', and 'cursor'. It sets 'appearance' to the specified value and the other properties to their appropriate system value; 'normal' resets 'appearance' to 'normal' and the others to 'inherit'. The 'appearance' property does not affect the specified or computed values of any other properties.
If 'appearance' is not 'normal', the UA must render the element as if it was the specified user interface (UI) control from the platform. The UA should use the computed values of the 'background-*', 'border-*', 'padding-*', 'outline-*', and 'text-decoration' properties when they do not have their initial values and the computed values of 'color', 'font', and 'cursor' (whatever their values) to influence the rendering where possible. Any values from those properties that cannot be used to influence the rendering of the UI control must not affect the rendering at all.
For example, the UA should not draw a second border around a UI control that already has a border.
If 'background-color' or 'background-image' have non-initial values and the UA is using their values for influencing the rendering of the UI control, then the UA must ensure that the 'color' property is also used to influence the rendering.
Other properties must not affect the handling of 'appearance' and must instead be applied according to normal CSS rules. In particular 'margin', 'display', 'float', 'height', 'width', and 'line-height', are not ignored and affect the element as normal.
This specification does not define the term "platform".
For example, it could be the native graphical rendering engine of the operating system, or it could be a user-agent-specific skin. In addition, which of several toolkits to use could also be decided on an element-by-element basis depending on the values of the 'background-color', 'background-image', 'border-*-style', and 'outline-style' properties, so that the author styles could be honored while still honoring 'appearance' even though the UA is unable to influence the rendering of OS native UI controls.
Note. The exact list of properties set by, influencing, and not affected by 'appearance' given in the lists above may be adjusted based on UA implementor feedback.
Appearance values take into account the user interface state (if any) of the element; thus there is no need for separate values for enabled vs. disabled checkboxes for example.
This example demonstrates setting the color and background-color of an
element that is set to 'appearance:push-button'.
input[type=button] {
appearance:push-button; /* expected from UA defaults */
}
input[type=button].custom {
color: #393;
background-color: #9cf;
}
<input type="button" value="Plain button" />
<input type="button" value="With color" class="custom" />
CSS2 introduced system font keywords as values for the shorthand 'font' property which have the effect of setting all the elemental 'font-*' properties. This specification adds the list of <appearance> values to the set of system fonts to allow styling text the same as such system controls.
| Name: | font |
| System values: | <appearance> | status-bar | message-box | caption | small-caption | inherit |
| Initial: | see individual properties in CSS 2.1 |
| Applies to: | all elements |
| Inherited: | yes |
| Percentages: | N/A for system values |
| Media: | visual |
| Computed value: | The computed values for system font keywords are simply the keywords themselves. |
This section is normative.
| Name: | content |
| New Value(s): | icon |
| Initial: | same as CSS 2.1 |
| Applies to: | same as CSS 2.1 |
| Inherited: | same as CSS 2.1 |
| Percentages: | same as CSS 2.1 |
| Media: | same as CSS 2.1 |
| Computed value: | the keyword 'icon' if specified as such, otherwise same as CSS 2.1 |
Note. It is expected that the next draft of the CSS3 Generated Content module [CSS3GENCON] will include and superset this functionality.
| Name: | icon |
| Value: | auto | <uri> [, <uri>]* | inherit |
| Initial: | auto |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | all |
| Computed value: | The computed value for 'auto' is 'auto'. The computed value for the <uri> value is either the fully qualified URI value for the referenced icon that the UA is able to render, or 'auto' if the UA did not find any referenced icons that it could render. |
The 'icon' property provides the author the ability to style any arbitrary element with an iconic equivalent. An element's icon is not used/rendered unless the 'content' property is set to the value 'icon' (see above). Documents whose elements have icons assigned to them can be more easily viewed by users who find too much text distracting.
This example uses the above icon features to display icons in place of images and objects.
img,object { content:icon }
/* note that the CSS3 Generated Content module [CSS3GENCON]
expands the 'content' property to apply to all elements. */
img { icon:url(imgicon.png); }
/* provide a custom icon for images */
object { icon:url(objicon.png); }
/* provide a different custom icon for objects */
This section is normative.
| Name: | box-sizing |
| Value: | content-box | border-box | inherit |
| Initial: | content-box |
| Applies to: | all elements that accept width or height |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | specified value |
Note. This is the behavior of width and height as commonly implemented by legacy HTML user agents for replaced elements and input elements.
This example uses box-sizing to evenly horizontally split two divs with fixed size borders inside a div container, which would otherwise require additional markup.
div.container {
width:38em;
border:1em solid black;
}
div.split {
box-sizing:border-box;
width:50%;
border:1em silver ridge;
float:left;
}
<div class="container">
<div class="split">This div occupies the left half.</div>
<div class="split">This div occupies the right half.</div>
</div>
This section is normative.
At times, style sheet authors may want to create outlines around visual objects such as buttons, active form fields, image maps, etc., to make them stand out. Outlines differ from borders in the following ways:
The outline properties control the style of these dynamic outlines.
| Name: | outline |
| Value: | [ <'outline-color'> || <'outline-style'> || <'outline-width'> ] | inherit |
| Initial: | see individual properties |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | undefined for shorthand properties |
| Name: | outline-width |
| Value: | <border-width> | inherit |
| Initial: | medium |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | <length> value in absolute units (px or physical). |
| Name: | outline-style |
| Value: | auto | <border-style> | inherit |
| Initial: | none |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | specified value |
| Name: | outline-color |
| Value: | <color> | invert | inherit |
| Initial: | invert |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | The computed value for 'invert' is 'invert'. For <color> values, the computed value is as defined for the [CSS3COLOR] 'color' property. |
The outline created with the outline properties is drawn "over" a box, i.e., the outline is always on top, and doesn't influence the position or size of the box, or of any other boxes. Therefore, displaying or suppressing outlines does not cause reflow.
Outlines may be non-rectangular. For example, if the element is broken across several lines, the outline should be an outline or minimum set of outlines that encloses all the element's boxes. Each part of the outline should be fully connected rather than open on some sides (as borders on inline elements are when lines are broken). The parts of the outline are not required to be rectangular. The position of the outline may be affected by descendant boxes. User agents should use an algorithm for determining the outline that encloses a region appropriate for conveying the concept of focus to the user.
The 'outline-width' property accepts the same values as 'border-width' ([CSS21], section 8.5.1).
The 'outline-style' property accepts the same values as 'border-style' ([CSS21], section 8.5.3), except that 'hidden' is not a legal outline style. In addition, in CSS3, 'outline-style' accepts the value 'auto'. The 'auto' value permits the user agent to render a custom outline style, typically a style which is either a user interface default for the platform, or perhaps a style that is richer than can be described in detail in CSS, e.g. a rounded edge outline with semi-translucent outer pixels that appears to glow. As such, this specification does not define how the 'outline-color' is incorporated or used (if at all) when rendering 'auto' style outlines. User agents may treat 'auto' as 'solid'.
The 'outline-color' property accepts all colors, as well as the keyword 'invert'. 'Invert' is expected to perform a color inversion on the pixels on the screen. This is a common trick to ensure the focus border is visible, regardless of color background.
Conformant UAs may ignore the 'invert' value on platforms that do not support color inversion of the pixels on the screen. If the UA does not support the 'invert' value then the initial value of the 'outline-color' property is the 'currentColor' [CSS3COLOR] keyword.
The 'outline' property is a shorthand property, and sets all three of 'outline-style', 'outline-width', and 'outline-color'.
Note. The outline is the same on all sides. In contrast to borders, there are no 'outline-top' or 'outline-left' etc. properties.
This specification does not define how multiple overlapping outlines are drawn, or how outlines are drawn for boxes that are partially obscured behind other elements.
Here's an example of drawing a thick outline around a BUTTON element:
button { outline: thick solid }
Graphical user interfaces may use outlines around elements to tell the user which element on the page has the focus. These outlines are in addition to any borders, and switching outlines on and off should not cause the document to reflow. The focus is the subject of user interaction in a document (e.g., for entering text, selecting a button, etc.).
For example, to draw a thick black line around an element when it has the focus, and a thick red line when it is active, the following rules can be used:
:focus { outline: thick solid black }
:active { outline: thick solid red }
Note. Since the outline does not affect formatting (i.e., no space is left for it in the box model), it may well overlap other elements on the page.
By default, the outline is drawn starting just outside the border edge. However, it is possible to offset the outline and draw it beyond the border edge.
| Name: | outline-offset |
| Value: | <length> | inherit |
| Initial: | 0 |
| Applies to: | all elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | <length> value in absolute units (px or physical). |
If the computed value of 'outline-offset' is anything other than 0, then the outline is outset from the border edge by that amount.
For example, to leave 2 pixels of space between a focus outline and the element that has the focus, or is active, the following rule can be used:
:focus,:active { outline-offset: 2px }
This section is normative.
CSS2.1 provides a mechanism for controlling the appearance of a scrolling mechanism (e.g. scrollbars), and this specification adds to that a mechanism for controlling user resizability of elements.
The 'resize' property allows the author to specify whether or not an element is resizable by the user, and if so, along which axis/axes.
| Name: | resize |
| Value: | none | both | horizontal | vertical | inherit |
| Initial: | none |
| Applies to: | elements with 'overflow' other than visible |
| Inherited: | no |
| Percentages: | N/A |
| Media: | visual |
| Computed value: | specified value. |
Currently it is possible to control the appearance of the scrolling
mechanism (if any) on an element using the 'overflow' property (e.g. 'overflow: scroll' vs. 'overflow:
hidden' etc.). The purpose of the 'resize' property is to also allow control over
the appearance and function of the resizing mechanism (e.g. a resize box or
widget) on the element.
Note. The resizing mechanism is NOT the same as the scrolling mechanism. The scrolling mechanism allows the user to determine which portion of the contents of an element is shown. The resizing mechanism allows the user to determine the size of the element.
The 'resize' property applies to elements whose computed 'overflow' value is something other than 'visible'. If 'overflow' is different in a particular axis (i.e. 'overflow-x' vs. 'overflow-y'), then this property applies to the dimension(s) which do not have the value 'visible'.
When an element is resized by the user, the user agent keeps track of a resize factor (which is initially 1.0) for the width and height, which it then applies to the computed width and height as part of determining the used width and height. The element's contents (and surroundings) are reformatted as necessary.
The resize factor introduces a step in width/height calculations and formatting as described in chapter 10 of CSS2.1. Specifically the following step is inserted between steps 1 and 2 of the algorithm in section 10.4 and 10.7 in CSS2.1 [CSS21], where [dimension] is 'width' for 10.4 and 'height' for 10.7.
1b. If the resize [dimension] factor is not 1.0, then the tentative used [dimension] is multiplied by that factor, and the rules above are applied again, but this time using the result of that multiplication as the computed value for '[dimension]'.
With regard to interactivity and the Document Object Model (DOM), the resize factor on an element lasts the lifetime of the element, however, if the 'resize' property itself is altered (e.g. via pseudo-class change or via DOM manipulation), then the resize factor is reset to 1.0.
The precise direction of resizing (i.e. altering the top left of the element or altering the bottom right) may depend on a number of factors including whether the element is absolutely positioned, whether it is positioned using the 'right' and 'bottom' properties, whether the language of the element is right-to-left etc. The precise direction of resizing is left to the UA to properly determine for the platform.
The user agent may restrict the resizing range to something suitable, such as between the original formatted size of the element, and large enough to encompass all the element's contents.
For example, to make iframes scrollable and resizable, the following rule can be used:
iframe,object[type^="text/"],
object[type$="+xml"],object[type="application/xml"]
{
overflow:auto;
resize:both;
}
This section is normative.
| Name: | cursor |
| Value: | [ [<uri> [<x> <y>]?,]* [ auto | default | none | context-menu | help | pointer | progress | wait | cell | crosshair | text | vertical-text | alias | copy | move | no-drop | not-allowed | e-resize | n-resize | ne-resize | nw-resize | s-resize | se-resize | sw-resize | w-resize | ew-resize | ns-resize | nesw-resize | nwse-resize | col-resize | row-resize | all-scroll ] ] | inherit |
| Initial: | auto |
| Applies to: | all elements |
| Inherited: | yes |
| Percentages: | N/A |
| Media: | visual, interactive |
| Computed value: | If there are one or more <uri> values specified, and the UA finds a <uri> that it is able to support (due to format, resource availability etc.), then the computed value is that resolved absolute URI, fully qualified, with optional <x> and <y> coordinates. If no such supported <uri> value is found, or if no <uri> values were specified, then the computed value is the specified keyword value. |
The UA may treat unsupported values as 'auto'. E.g. on platforms that do not have a concept of a 'context-menu' cursor, the UA may render 'default' or whatever is appropriate.
Here is an example of using several cursor values.
:link,:visited {
cursor: url(example.svg#linkcursor),
url(hyper.cur),
url(hyper.png) 2 3,
pointer
}
This example sets the cursor on all hyperlinks (whether visited or not) to an external SVG cursor ([SVG10], section 16.8.3). User agents that don't support SVG cursors would simply skip to the next value and attempt to use the "hyper.cur" cursor. If that cursor format was also not supported, the UA could attempt to use the "hyper.png" cursor with the explicit hot spot. Finally if the UA does not support any of those image cursor formats, the UA would skip to the last value and simply render the 'pointer' cursor.
The 'nav-index' property is an input-method-neutral way of specifying the sequential navigation order (also known as "tabbing order").
| Name: | nav-index |
| Value: | auto | <number> | inherit |
| Initial: | auto |
| Applies to: | all enabled elements |
| Inherited: | no |
| Percentages: | n/a |
| Media: | interactive |
| Computed value: | specified value. |
This property is a replacement for the HTML4/XHTML1 attribute 'tabindex' ([HTML401], section 17.11.1). Borrowed and slightly rephrased from the HTML4 Recommendation:
This property specifies the position of the current element in the sequential navigation order for the current document.
The sequential navigation order defines the order in which elements will receive focus when navigated by the user via the keyboard. The sequential navigation order may include elements nested within other elements.
Elements that may receive focus should be navigated by user agents according to the following rules:
The actual key sequence that causes sequential navigation or element activation depends on the configuration of the user agent (e.g., the "tab" key is often used for sequential navigation, and the "enter" key is used to activate a selected element).
User agents may also define key sequences to navigate the sequential navigation order in reverse. When the end (or beginning) of the tabbing order is reached, user agents may circle back to the beginning (or end). The key combination "shift-tab" is often used for reverse sequential navigation.
| Names: | nav-up, nav-right, nav-down, nav-left |
| Value: | auto | <id> [ current | root | <target-name> ]? | inherit |
| Initial: | auto |
| Applies to: | all enabled elements |
| Inherited: | no |
| Percentages: | N/A |
| Media: | interactive |
| Computed value: | <id> as specified with <target-name> string or keyword. |
The <id> value consists of a '#' character followed by
an identifier, similar to a fragment identifier in a URL. It indicates the
element to which the focus is navigated to in response to directional
navigation input respective to the specific property.
If the <id> refers to the currently focused element, the directional navigation input respective to the nav- property is ignored — there is no need to refocus the same element.
User agents for devices with directional navigation keys respond by navigating the focus according to four respective nav-* directional navigation properties (nav-up, nav-right, nav-down, nav-left). This specification does not define which keys of a device are directional navigational keys.
Note. Typical personal computers have keyboards with four arrow keys. One possible implementation would be to use those four arrow keys for directional navigation. For accessibility and user convenience, user agents should allow configuration of which keys on a keyboard are used for directional navigation.
Here is an example of buttons positioned in a diamond shape whose navigation order and directional focus navigation is set in such a way to navigate the focus clockwise (or counter-clockwise) around the diamond shape when the user chooses to navigate sequentially or directionally.
button { position:absolute }
button#b1 {
top:0; left:50%;
nav-index:1;
nav-right:#b2; nav-left:#b4;
nav-down:#b2; nav-up:#b4;
}
button#b2 {
top:50%; left:100%;
nav-index:2;
nav-right:#b3; nav-left:#b1;
nav-down:#b3; nav-up:#b1;
}
button#b3 {
top:100%; left:50%;
nav-index:3;
nav-right:#b4; nav-left:#b2;
nav-down:#b4; nav-up:#b2;
}
button#b4 {
top:50%; left:0;
nav-index:4;
nav-right:#b1; nav-left:#b3;
nav-down:#b1; nav-up:#b3;
}
Whatever markup sequence the buttons may have (which is not specified in this example) is irrelevant in this case because they are positioned, and yet, it is still important to ensure focus navigation behaviors which relate reasonably to the specified layout.
This appendix is informative.
Thanks to feedback and contributions from L. David Baron, Bert Bos, Matthew Brealey, Ada Chan, Michael Day, Micah Dubinko, Elika E., Steve Falkenburg, Al Gilman, Ian Hickson, Bjoern Hoehrmann, David Hyatt, Richard Ishida, Sho Kuwamoto, Susan Lesch, Peter Linss, Brad Pettit, Alexander Savenkov, Sebastian Schnitzenbaumer, Etan Wexler, David Woolley and Domel.
This appendix is normative.
This appendix is informative.
In general this draft contains numerous editorial/grammatical/spelling corrections, and several new informative examples. This appendix describes minor functional changes from the Last Call Working Draft of 3 July 2003 that were made to accommodate last call comments.
This appendix is informative.
Potential additions to the base style sheet to express HTML4/XHTML1 form controls and a few HTML4/XHTML1 dynamic presentation attributes:
:link,:visited {
appearance: hyperlink; /* set color, font, background, padding, border, etc.*/
}
:enabled:focus {
outline: 2px inset;
}
button,
input[type=button],
input[type=reset],
input[type=submit],
input[type=checkbox],
input[type=radio],
textarea,
input,
input[type=text],
input[type=hidden],
input[type=password],
input[type=image]
{
appearance: button;
display: inline-block;
white-space: nowrap;
}
button,
input[type=button],
input[type=reset][value],
input[type=submit][value]
{
/* appearance of HTML4/XHTML1 push buttons */
appearance: push-button;
}
button
{
/* white space handling of BUTTON tags in particular */
white-space:normal;
}
input[type=reset]
{
/* default content of HTML4/XHTML1 input type=reset button */
content: "Reset";
}
input[type=submit]
{
/* default content of HTML4/XHTML1 input type=submit button */
content: "Submit";
}
input[type=button],
input[type=reset][value],
input[type=submit][value]
{
/* text content/labels of HTML4/XHTML1 "input" buttons */
content: attr(value);
}
input[type=checkbox]
{
appearance:checkbox;
}
input[type=radio]
{
appearance:radio-button;
}
textarea,
input,
input[type=text],
input[type=hidden],
input[type=password]
{
appearance: field;
}
textarea
{
/* white space handling of TEXTAREA tags in particular */
white-space:pre-wrap;
}
input[type=password]
{
appearance: password;
}
input[type=hidden]
{
/* appearance of the HTML4/XHTML1 hidden text field in particular */
display: none;
}
input[type=image]
{
display: inline-block;
content: attr(src,url);
border: none;
}
select[size]
{
/* HTML4/XHTML1 <select> w/ size more than 1 - appearance of list */
appearance: list-menu;
display: inline-block;
height: attr(size,em);
}
select,select[size=1]
{
/* HTML4/XHTML1 <select> without size, or size=1 - popup-menu */
appearance: popup-menu;
display: inline-block;
height: 1em;
overflow: hidden;
}
option
{
appearance:menu-item;
}
select[size]:active
{
/* active HTML4/XHTML <select> w/ size more than 1 - appearance of active list */
display: inline-block;
}
optgroup,option
{
display: block;
white-space: nowrap;
}
optgroup[label],option[label]
{
content: attr(label);
}
option[selected]::before
{
display: inline;
content: check;
}
*[tabindex] { nav-index:attr(tabindex,number) }
/* Though FRAME resizing is not directly addressed by this specification,
the following rules may provide an approximation of reasonable behavior. */
/*
frame { resize:both }
frame[noresize] { resize:none }
*/
This appendix is informative.
These example profiles are written to roughly reflect the set of functionality that other specifications use/define which has been explicitly defined and/or updated in this specification. These profiles are independent of any other dimensions of variability, e.g. properties that may allow some values to be treated as other values.
This specification recommends that implementations base their support on at least one of the profiles defined below. Thus a CSS2.1 user agent for example, should consider supporting the CSS2.1 profile for CSS3 Basic UI.
| CSS3 Basic User Interface profile | |
|---|---|
| Specification | CSS level 1 |
| Accepts | :active pseudo-class on hyperlinks |
| Excludes | :hover, :active on non-hyperlinks, :focus, :enabled, :disabled,
:checked, :indeterminate pseudo-classes :default, :valid, :invalid, :in-range, :out-of-range, :required, :optional, :read-only, :read-write pseudo-classes ::selection, ::value, ::choices, ::repeat-item, ::repeat-index pseudo-elements 'appearance' property 'font' property keyword additions 'icon' keyword value for 'content' property 'box-sizing' property 'outline', 'outline-width', 'outline-style', 'outline-color', 'outline-offset' properties 'resize' property 'cursor' property 'nav-index', 'nav-up', 'nav-right', 'nav-down', 'nav-left' properties |
| Extra constraints | none. |
| CSS3 Basic User Interface profile | |
|---|---|
| Specification | CSS level 2 revision 1 |
| Accepts | :hover, :active, :focus pseudo-classes 'font' property keyword values: 'caption', 'icon', 'menu', 'message-box', 'small-caption', 'status-bar'. 'outline', 'outline-width', 'outline-style', 'outline-color' properties. 'cursor' property |
| Excludes | :enabled, :disabled, :checked, :indeterminate pseudo-classes :default, :valid, :invalid, :in-range, :out-of-range, :required, :optional, :read-only, :read-write pseudo-classes ::selection, ::value, ::choices, ::repeat-item, ::repeat-index pseudo-elements 'appearance' property 'font' property keyword additions 'icon' keyword value for 'content' property 'box-sizing' property 'outline-offset' property 'resize' property 'cursor' property additions 'nav-index', 'nav-up', 'nav-right', 'nav-down', 'nav-left' properties |
| Extra constraints | 'cursor' property support omits hotspot for downloaded cursors, and new cursor keyword values. 'outline-style' property does not support 'auto' value. |
| CSS3 Basic User Interface profile | |
|---|---|
| Specification | XForms 1.0 |
| Accepts | :hover, :active, :focus, :enabled, :disabled, :checked, :indeterminate
pseudo-classes :default, :valid, :invalid, :in-range, :out-of-range, :required, :optional, :read-only, :read-write pseudo-classes ::value, ::choices, ::repeat-item, ::repeat-index pseudo-elements |
| Excludes | ::selection pseudo-element 'appearance' property 'outline', 'outline-width', 'outline-style', 'outline-color' properties. 'cursor' property 'font' property keyword additions 'icon' keyword value for 'content' property 'box-sizing' property 'outline-offset' property 'resize' property 'cursor' property additions 'nav-index', 'nav-up', 'nav-right', 'nav-down', 'nav-left' properties |
| Extra constraints | none. |
| CSS3 Basic User Interface profile | |
|---|---|
| Specification | CSS3 |
| Accepts | :hover, :active, :focus, :enabled, :disabled, :checked, :indeterminate
pseudo-classes :default, :valid, :invalid, :in-range, :out-of-range, :required, :optional, :read-only, :read-write pseudo-classes ::selection, ::value, ::choices, ::repeat-item, ::repeat-index pseudo-elements 'appearance' property 'outline', 'outline-width', 'outline-style', 'outline-color' properties. 'cursor' property 'font' property keyword additions 'icon' keyword value for 'content' property 'box-sizing' property 'outline-offset' property 'resize' property 'cursor' property additions 'nav-index', 'nav-up', 'nav-right', 'nav-down', 'nav-left' properties |
| Excludes | none. |
| Extra constraints | none. |
This appendix is informative.
This specification shall refer to a test suite written according to the CSS Test Suite Documentation and following the CSS2.1 Test Case Authoring Guidelines. The test suite shall allow user agents to verify their basic conformance to the specification. This test suite does not pretend to be exhaustive and does not cover all possible combinations of user interface related features. These tests will be made available from the CSS Test Suites home page.
This appendix is informative.
This appendix is informative.
| Property | Values | Initial | Applies to | Inh. | Percentages | Media |
|---|---|---|---|---|---|---|
| appearance | normal | <appearance> | inherit | normal | all elements | no | N/A | visual, interactive |
| box-sizing | content-box | border-box | inherit | content-box | all elements that accept width or height | no | N/A | visual |
| content | icon | same as CSS 2.1 | same as CSS 2.1 | same as CSS 2.1 | same as CSS 2.1 | same as CSS 2.1 |
| cursor | [ [<uri> [<x> <y>]?,]* [ auto | default | none | context-menu | help | pointer | progress | wait | cell | crosshair | text | vertical-text | alias | copy | move | no-drop | not-allowed | e-resize | n-resize | ne-resize | nw-resize | s-resize | se-resize | sw-resize | w-resize | ew-resize | ns-resize | nesw-resize | nwse-resize | col-resize | row-resize | all-scroll ] ] | inherit | auto | all elements | yes | N/A | visual, interactive |
| font | <appearance> | status-bar | message-box | caption | small-caption | inherit | see individual properties in CSS 2.1 | all elements | yes | N/A for system values | visual |
| icon | auto | <uri> [, <uri>]* | inherit | auto | all elements | no | N/A | all |
| nav-index | auto | <number> | inherit | auto | all enabled elements | no | n/a | interactive |
| nav-up, nav-right, nav-down, nav-left | auto | <id> [ current | root | <target-name> ]? | inherit | auto | all enabled elements | no | N/A | interactive |
| outline | [ <'outline-color'> || <'outline-style'> || <'outline-width'> ] | inherit | see individual properties | all elements | no | N/A | visual |
| outline-color | <color> | invert | inherit | invert | all elements | no | N/A | visual |
| outline-offset | <length> | inherit | 0 | all elements | no | N/A | visual |
| outline-style | auto | <border-style> | inherit | none | all elements | no | N/A | visual |
| outline-width | <border-width> | inherit | medium | all elements | no | N/A | visual |
| resize | none | both | horizontal | vertical | inherit | none | elements with 'overflow' other than visible | no | N/A | visual |