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.
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 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 “css3-ui” in the subject, preferably like this:
“[css3-ui] …summary of
comment…”
This specification is a Last Call Working Draft,
although it was previously a Candidate Recommendation. It has been
returned to Last Call Working Draft because this draft removes features
that were not implemented sufficiently to advance to Proposed
Recommendation, and had not been previously listed as at risk, as required
by the W3C Process. This draft also adds a couple of new properties and
values. See Appendix C. Changes for further
details.
All persons are encouraged to review this document and send comments to
the www-style
mailing list as described above. The deadline for
comments is four weeks after the date of publication in the
header or 14 February 2012, whichever is sooner.
Candidate Recommendation Exit Criteria
For this specification to enter the Proposed Recommendation stage, the
following conditions shall be met:
There must be at least two interoperable implementations for every
feature. For the purposes of this criterion, we define the following
terms:
feature
A section or subsection of the specification.
interoperable
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.
implementation
a user agent which:
implements the feature.
is available (i.e. publicly downloadable or available through some
other public point of sale mechanism). This is the "show me"
requirement.
is shipping (i.e. development, private or unofficial versions are
insufficient).
is not experimental (i.e. is intended for a wide audience and
could be used on a daily basis).
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 CSS Basic User Interface Module Level 3 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 are
believed to have two or more implementations, and thus will not be dropped
without returning to last call.
‘text-overflow’ property 2-value syntax
and definition.
Overview
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.
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.
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.
1.1. Purpose
The purpose of this specification is to achieve the following
objectives:
Extend the user interface features in CSS2.1.
Provide additional CSS mechanisms to augment or replace other dynamic
presentation related features in HTML4/XHTML1.
Introduce directional navigation properties to assist in the
construction of user interfaces which make use of a directional
navigation model.
Introduce properties and values to specify icon presentations for
elements to enhance accessibility.
2. Conformance
2.1. Definitions
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.
The following classes of products (many of which overlap) should
consider implementing this specification:
Web browsers
User agents that implement one or more of the following types of
content: HTML ([HTML401], [HTML5]), XHTML ([XHTML10], [XHTML11]), XForms (e.g. [XFORMS11]), SVG
(e.g. [SVG10], [SVG11]) or other
content languages that contain forms controls or are intended for user
interaction
User agents that implement one or more levels or modules of CSS (e.g.
[CSS1], [CSS21])
2.3. Extensions
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 4.1.2.1).
3.
Dependencies on other modules
This CSS3 module depends on the following other specifications.
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.
4.1.1. :active details
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.
4.1.2. The
indeterminate-value pseudo-class ‘:indeterminate’
The :indeterminate pseudo-class applies to UI elements
whose value is in an indeterminate state. For example, radio and checkbox
elements can be toggled between checked and unchecked states, but are
sometimes in an indeterminate state, neither checked nor unchecked.
Similarly a progress meter can be in an indeterminate state when the
percent completion is unknown.
Like the :checked pseudo-class, :indeterminate
applies to all media. Components of a radio-group initialized with no
pre-selected choice, for example, would be :indeterminate
even in a static display.
New
user interface state pseudo-classes
In addition to the above-mentioned pseudo-classes, this specification
introduces several new pseudo-classes to define additional user interface
states.
:default
:valid
:invalid
:in-range
:out-of-range
:required
:optional
:read-only
:read-write
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 [XFORMS11].
4.1.3. :default
The :default selector applies to the one or more UI elements that are
the default among a set of similar elements. This selector 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.
4.1.4. :valid and :invalid
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. [XFORMS11]). 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.
4.1.5. :in-range and :out-of-range
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".
4.1.6. :required and :optional
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.
4.1.7. :read-only and :read-write
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.
4.2. User interface element
fragments: pseudo-elements
In addition to the above-mentioned pseudo-element, this specification
introduces four new pseudo-elements to provide access to additional user
interface element fragments.
::value
::choices
::repeat-item
::repeat-index
Specifically, these new pseudo-elements are provided as a way to style
user interface fragments as defined by XForms [XFORMS11].
Note: The ::value, ::choices, ::repeat-item, and
::repeat-index pseudo-elements are all at risk.
4.2.1. ::value
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.
Example(s):
fictional
markup and illustration
Here is an example which illustrates the ::value of a text input field
with fictional markup which is then styled with CSS.
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.
The ::value pseudo-element is similar to an inline-level element, but
with certain restrictions. The following properties apply to
::value pseudo-element: font properties, color property,
background properties, ‘word-spacing’, ‘letter-spacing’, ‘text-decoration’, ‘vertical-align’, ‘text-transform’, ‘line-height’. UAs may apply other properties
as well.
4.2.2. ::choices
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.
4.2.3. ::repeat-item
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.
4.2.4. ::repeat-index
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.
Example(s):
::repeat-item and
::repeat-index fictional markup
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:
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.
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.
as specified, except with any relative URLs converted to absolute
auto
Use a default generic icon provided by the user agent.
<uri>
URIs (see [URI], [RFC1738] and [RFC1808]) provide
a way of identifying resources. The <uri> value(s) in this property
refer to one or more icons in a comma delimited list. The user agent
loads the referenced icons one by one until it finds one that it is able
to render. This permits the usage of multiple different icon formats for
various platforms, and various media for that matter.
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.
Example(s):
Representing
elements with icons
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 is the behavior of width and height as specified by CSS2.1. The
specified width and height (and respective min/max properties) apply to
the width and height respectively of the content box of the element. The
padding and border of the element are laid out and drawn outside the
specified width and height.
padding-box
The specified width and height (and respective min/max properties) on
this element determine the padding box of the element. That is, any
padding specified on the element is laid out and drawn inside this
specified width and height. The content width and height are calculated
by subtracting the padding widths of the respective sides from the
specified ‘width’ and ‘height’
properties. As the content width and height cannot
be negative ([CSS21], section 10.2), this
computation is floored at 0.
border-box
The specified width and height (and respective min/max properties) on
this element determine the border box of the element. That is, any
padding or border specified on the element is laid out and drawn inside
this specified width and height. The content width and height are
calculated by subtracting the border and padding widths of the respective
sides from the specified ‘width’ and ‘height’
properties. As the content width and height cannot
be negative ([CSS21], section 10.2), this
computation is floored at 0.
Note. This is the behavior of width
and height as commonly implemented by legacy HTML user agents for
replaced elements and input elements.
Example(s):
Using
box-sizing to evenly share space
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 class="container">
<div class="split">This div occupies the left half.</div>
<div class="split">This div occupies the right half.</div>
</div>
demonstration of sample CSS and
HTML:
This
div should occupy the left half.
This
div should occupy the right half.
The two divs above should appear side by side, each (including borders)
50% of the content width of their container. If instead they are stacked
one on top of the other then your browser does not support ‘box-sizing’.
Note: The ‘padding-box’ value is at risk.
7. Outline properties
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:
Outlines do not take up space.
Outlines may be non-rectangular.
The outline properties control the style of these dynamic outlines.
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-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.
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.
Example(s):
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.).
Example(s):
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.
Example(s):
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 }
8. Resizing &
Overflow
CSS2.1 provides a mechanism for controlling the appearance of a
scrolling mechanism (e.g. scrollbars) on block container elements. This
specification adds to that a mechanism for controlling user resizability
of elements as well as the ability to specify text overflow behavior.
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.
none
The UA does not present a resizing mechanism on the element, and the
user is given no direct manipulation mechanism to resize the element.
both
The UA presents a bidirectional resizing mechanism to allow the user
to adjust both the height and the width of the element.
horizontal
The UA presents a unidirectional horizontal resizing mechanism to
allow the user to adjust only the width of the element.
vertical
The UA presents a unidirectional vertical resizing mechanism to allow
the user to adjust only the height of the element.
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.
Example(s):
For example, to make iframes scrollable and resizable, the
following rule can be used:
This property specifies rendering when inline content overflows its
block container element ("the block") in its inline progression direction
that has ‘overflow’ other than ‘visible’. Text
can overflow for example when it is prevented from wrapping (e.g. due to
‘white-space:nowrap’ or a
single word is too long to fit). Values have the following meanings:
clip
Clip inline content that overflows. Characters may be only partially
rendered.
ellipsis
Render an ellipsis character (U+2026) to represent clipped inline
content. Implementations may substitute a more
language/script-appropriate ellipsis character, or three dots "..." if
the ellipsis character is unavailable.
<string>
Render the given string to represent clipped inline content. The
given string is treated as an independent paragraph for bidi purposes.
Note: The <string> value, and the 2-value syntax
"{1,2}" and functionality are all at risk.
The term "character" is used in this property definition for better
readability and means "grapheme cluster" [UAX29] for implementation purposes.
If there is one value, it applies only to the end line edge. If there
are two values, the first value applies to the left edge, and the second
value applies to the right edge.
For the ellipsis and string values, implementations must hide
characters and atomic
inline-level elements at the applicable edge(s) of the line as
necessary to fit the ellipsis/string. Place the ellipsis/string
immediately adjacent to the applicable edge(s) of the remaining inline
content. The first character or atomic
inline-level element on a line must be clipped rather than ellipsed.
ellipsing details
Ellipsing only affects rendering and must not affect layout nor
dispatching of pointer events.
The ellipsis is styled and baseline-aligned according to the block.
Ellipsing occurs after relative positioning and other graphical
transformations.
If there is insufficient space for the ellipsis, then clip the
rendering of the ellipsis itself (on the same side that neutral
characters on the line would have otherwise been clipped with the
‘clip’ value).
When the user is interacting with content (e.g. editing, selecting,
scrolling), the user agent may treat text-overflow ‘ellipsis’ or string values as ‘clip’.
Example(s):
text-overflow examples
These examples demonstrate setting the text-overflow of a block
container element that has text which overflows its dimensions:
Note: the side of the line that the ellipsis is placed
depends on the ‘direction’ of the
block. E.g. an overflow hidden right-to-left (direction:rtl)
block clips inline content on the left side, thus would place a
text-overflow ellipsis on the left to represent that clipped
content.
ellipsis interaction with
scrolling interfaces
This section applies to elements with text-overflow other than
‘clip’ (non-clip text-overflow)
and overflow:scroll.
When an element with non-clip text-overflow has overflow of scroll in
the inline progression dimension of the text, and the browser provides a
mechanism for scrolling (e.g. a scrollbar on the element, or a touch
interface to swipe-scroll, etc.), there are additional implementation
details that provide a better user experience:
When an element is scrolled (e.g. by the user, DOM manipulation, or ‘overflow-style’[CSS3MARQUEE]), more of the
element's content is shown. The value of text-overflow should not affect
whether more of the element's content is shown or not. If a non-clip
text-overflow is set, then as more content is scrolled into view,
implementations should show whatever additional content fits, only
truncating content which would otherwise be clipped (or is necessary to
make room for the ellipsis/string), until the element is scrolled far
enough to display the edge of the content at which point that content
should be displayed rather than an ellipsis/string.
As some content is scrolled into view, it is likely that other content
may scroll out of view on the other side. If that content's block
container element is the same that's doing the scrolling, then
implementations should render an ellipsis/string in place of the clipped
content, with the same details as described in the value definition above,
except that the ellipsis/string is drawn in the start (rather than end) of
the block's direction (per the direction property).
While the content is being scrolled, implementations may adjust their
rendering of ellipses/strings (e.g. align to the box edges rather than
line edges).
If there is insufficient space for both start and end ellipses/strings,
then only the end ellipsis/string should be rendered.
as specified, except with any relative URLs converted to absolute
This property specifies the type of cursor to be displayed for the
pointing device when over the element's border, padding, and content.
Values have the following meanings:
image cursors
<uri>
The user agent retrieves the cursor from the resource designated by
the URI. If the user agent cannot handle the first cursor of a list of
cursors, it must attempt to handle the second, etc. If the user agent
cannot handle any user-defined cursor, it must use the cursor keyword at
the end of the list. The optional <x> and <y> coordinates
identify the exact position within the image which is the pointer
position (i.e., the hotspot).
<x>
<y>
Each is a <number>. The x-coordinate and y-coordinate of the
position in the cursor's coordinate system (left/top relative) which
represents the precise position that is being pointed to. If the values
are unspecified, then the intrinsic hotspot defined inside the image
resource itself is used. If both the values are unspecific and the
referenced cursor has no defined hotspot, the effect is as if a value of
"0 0" were specified.
general purpose
cursors
auto
The UA determines the cursor to display based on the current context.
default
The platform-dependent default cursor. Often rendered as an arrow.
none
No cursor is rendered for the element.
links and status
cursors
context-menu
A context menu is available for the object under the cursor. Often
rendered as an arrow with a small menu-like graphic next to it.
help
Help is available for the object under the cursor. Often rendered as a
question mark or a balloon.
pointer
The cursor is a pointer that indicates a link.
progress
A progress indicator. The program is performing some processing, but
is different from ‘wait’ in that the user may still interact
with the program. Often rendered as a spinning beach ball, or an arrow
with a watch or hourglass.
wait
Indicates that the program is busy and the user should wait. Often
rendered as a watch or hourglass.
selection cursors
cell
Indicates that a cell or set of cells may be selected. Often rendered
as a thick plus-sign with a dot in the middle.
crosshair
A simple crosshair (e.g., short line segments resembling a "+" sign).
Often used to indicate a two dimensional bitmap selection mode.
text
Indicates text that may be selected. Often rendered as a vertical
I-beam. User agents may automatically display a horizontal I-beam/cursor
(e.g. same as the ‘vertical-text’ keyword) for vertical
text, or for that matter, any angle of I-beam/cursor for text that is
rendered at any particular angle.
vertical-text
Indicates vertical-text that may be selected. Often rendered as a
horizontal I-beam.
drag and drop cursors
alias
Indicates an alias of/shortcut to something is to be created. Often
rendered as an arrow with a small curved arrow next to it.
copy
Indicates something is to be copied. Often rendered as an arrow with a
small plus sign next to it.
move
Indicates something is to be moved.
no-drop
Indicates that the dragged item cannot be dropped at the current
cursor location. Often rendered as a hand or pointer with a small circle
with a line through it.
not-allowed
Indicates that the requested action will not be carried out. Often
rendered as a circle with a line through it.
Indicates that some edge is to be moved. For example, the ‘se-resize’ cursor is used when the movement
starts from the south-east corner of the box.
ew-resize, ns-resize, nesw-resize, nwse-resize
Indicates a bidirectional resize cursor.
col-resize
Indicates that the item/column can be resized horizontally. Often
rendered as arrows pointing left and right with a vertical bar separating
them.
row-resize
Indicates that the item/row can be resized vertically. Often rendered
as arrows pointing up and down with a horizontal bar separating them.
all-scroll
Indicates that the something can be scrolled in any direction. Often
rendered as arrows pointing up, down, left, and right with a dot in the
middle.
zooming cursors
zoom-in, zoom-out
Indicates that something can be zoomed (magnified) in or out, and
often rendered as a magnifying glass with a "+" or "-" in the center of
the glass, for ‘zoom-in’ and
‘zoom-out’ respectively.
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.
Example: cursor
fallback
Here is an example of using several cursor values.
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.
9.2. Keyboard control
9.2.1. Sequential navigation
order: the ‘nav-index’ property
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.
auto
The element's sequential navigation order is assigned automatically by
the user agent.
<number>
The number (which is non-zero and positive) indicates the sequential
navigation order for the element. ‘1’ means first. Elements with the same
nav-index value are navigated in document order when that nav-index value
is being navigated.
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:
Those elements that support the nav-index property and assign a
positive value to it are navigated first. Navigation proceeds from the
element with the lowest nav-index value to the element with the highest
value. Values need not be sequential nor must they begin with any
particular value. Elements that have identical nav-index values should be
navigated in document order.
Those elements that do not support the nav-index property or support
it and assign it a value of ‘auto’ are navigated next. These elements
are navigated in document order.
Elements that are disabled do not participate in the sequential
navigation order.
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.
auto | <id> [ current | root | <target-name> ]? |
inherit
Initial:
auto
Applies to:
all enabled elements
Inherited:
no
Percentages:
N/A
Media:
interactive
Computed value:
as specified
auto
The user agent automatically determines which element to navigate the
focus to in response to directional navigational input.
<id>
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.
<target-name>
The <target-name> parameter indicates the target frame for the
focus navigation. It is a string and it cannot start with the underscore
"_" character. If the specified target frame does not exist, the
parameter will be treated as the keyword ‘current’, which means to simply use the
frame that the element is in. The keyword ‘root’ indicates that the user agent
should target the full window.
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.
Example:
positioned buttons
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.
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 example disables input method support for a field; this might be
necessary for fields that enter data into a database that doesn't support
extended character sets, for example.
Example: user
preference
input[type=password] {
ime-mode: auto !important;
}
This example CSS may be placed into a user style sheet file to force
password input fields to behave in a default manner.
Note: In general, it's not appropriate for a public web site
to manipulate the IME mode setting. This property should be used for web
applications and the like. Authors should not rely on disabling IME to
prevent extended characters from passing through a form. Even with IME
disabled, users can still paste extended characters into a form's fields.
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.
In general this draft contains numerous editorial/grammatical/spelling
corrections, and several new informative examples. This appendix describes
minor functional changes from the Candidate
Recommendation (CR) of 11 May 2004 that were made to reflect
implementer adoption (or lack thereof) in the seven years since. In
particular, changes since the CR fall into one of three categories:
Minor refinements to features based on implementation experience.
Dropping features that were not implemented, or were insufficiently
implemented to exit CR.
Adding a small number of new but already interoperably implemented
features.
List of substantial changes
System Appearance has been dropped, including appearance values &
property, and system fonts / extension of the ‘font’ property shorthand.
The ::selection pseudo-element has been dropped since it was dropped
from Selectors after testing found interoperability problems and further
details to explore/define.
Appendix D.
Default style sheet additions for HTML
This appendix is informative.
Potential additions to the base style sheet to express HTML form
controls, and a few dynamic presentation attributes:
: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]
{
display: inline-block;
white-space: nowrap;
}
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);
}
textarea
{
/* white space handling of TEXTAREA tags in particular */
white-space:pre-wrap;
}
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 */
display: inline-block;
height: attr(size,em);
}
select,select[size=1]
{
/* HTML4/XHTML1 <select> without size, or size=1 - popup-menu */
display: inline-block;
height: 1em;
overflow: hidden;
}
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 }
*/
Appendix E: Test Suite
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.