Some properties accept arbitrary author-defined identifiers as a component value. This generic data type is denoted by <custom-ident>, and represents any valid CSS identifier that does not otherwise appear as a pre-defined keyword in that property's value definition. Such identifiers are fully case-sensitive, even in the ASCII range (e.g. ‘example’ and ‘EXAMPLE’ are two different, unrelated user-defined identifiers).

]]> The touch-action CSS property determines whether touch input may trigger default behavior supplied by user agent. This includes, but is not limited to, behaviors such as panning or zooming.

]]> Same as :(1).

The :last-child pseudo-class represents an element that is the last child of some other element.


The following selector represents a list item li that is the last child of an ordered list ol.


ol > li:last-child]]> Same as :(1).

The :first-of-type pseudo-class represents an element that is the first sibling of its type in the list of children of its parent element.

]]> Same as :(1).

The :last-of-type pseudo-class represents an element that is the last sibling of its type in the list of children of its parent element.


The following selector represents the last data cell td of a table row tr.


tr > td:last-of-type.]]> Represents an element that has a parent element and whose parent element has no other element children.


Same as :: or :(1):(1), but with a lower specificity.

]]> Represents an element that has a parent element and whose parent element has no other element children with the same expanded element name.


Same as :: or :(1):(1), but with a lower specificity.

]]> The :empty pseudo-class represents an element that has no children at all.

In terms of the document tree, only element nodes and content nodes whose data has a non-zero length must be considered as affecting emptiness; comments, processing instructions, and other nodes must not affect whether an element is considered empty or not.


p:empty is a valid representation of the following fragment:

<p></p>

foo:empty is not a valid representation for the following fragments:

<foo>bar</foo>
<foo><bar>bla</bar></foo>
<foo>this is not <bar>:empty</bar></foo>
]]> :target pseudo-class selects the target element of the referring URI. A fragment identifier is used to identify a location within a document, and is formed using a number sign followed by an anchor identifier—for example, http://www.example.com/mypage.html#section_3.]]> :enabled pseudo-class is a UI element states pseudo-class. UI element states pseudo-classes select UI elements (form controls such as radio buttons or check boxes) that are in a certain state—enabled, disabled, or selected (checked).]]> :disabled pseudo-class is a UI element states pseudo-class. UI element states pseudo-classes select UI elements (form controls such as radio buttons or check boxes) that are in a certain state—enabled, disabled, or selected (checked).]]> Radio and checkbox elements can be toggled by the user, but are sometimes in an indeterminate state, neither checked nor unchecked. This can be due to an element attribute, or DOM manipulation.

A future version of CSS3-selectors specification may introduce an :indeterminate pseudo-class that applies to such elements.]]> :fullscreen pseudo-class must match the top element of the document's fullscreen element stack (if any).]]> ::first-letter pseudo-element must select the first letter of the first line of a block, if it is not preceded by any other content (such as images or inline tables) on its line.]]> The ::first-line pseudo-element applies special styles to the contents of the first formatted line of a paragraph.

]]> ::backdrop pseudo-element. This pseudo-element is a box rendered immediately below the element (and above the element below the element in the stack, if any), within the same top layer. The ::backdrop pseudo-element can be used to create a backdrop that hides the underlying document for an element in the top layer's stack. E.g. for the element that is displayed fullscreen as described by this specification. It does not inherit from any element and is not inherited from. No restrictions are made on what properties apply to this pseudo-element either.]]> The ::cue pseudo-element (with no argument) matches any list of WebVTT Node Objects constructed for the matched element, with the exception that the properties corresponding to the background shorthand must be applied to the WebVTT cue background box rather than the list of WebVTT Node Objects.

The ::cue(selector) pseudo-element with an argument matches any WebVTT Internal Node Object constructed for the matched element that also matches the given CSS selector.

]]> The ::cue-region pseudo-element (with no argument) matches any list of WebVTT region objects constructed for the matched element.

The ::cue-region(selector) pseudo-element with an argument matches any list of WebVTT region objects constructed for the matched element that also matches the given CSS selector.

]]> The :nth-child CSS pseudo-class matches an element that has an+b-1 siblings before it in the document tree, for a given positive or zero value for n, and has a parent element.

This can more clearly be described this way: the matching element is the bth child of an element after all its children have been split into groups of a elements each.

Syntax

element:nth-child(an + b) {}

]]> The :nth-last-child CSS pseudo-class matches an element that has an+b-1 siblings after it in the document tree, for a given positive or zero value for n, and has a parent element.

See : for a more thorough description of the syntax of its argument.

Syntax

element:nth-last-child(an + b) {}

]]> The :nth-of-type CSS pseudo-class matches an element that has an+b-1 siblings with the same element name before it in the document tree, for a given positive or zero value for n, and has a parent element.

See : for a more thorough description of the syntax of its argument.

Syntax

element:nth-of-type(an + b) {}

]]> The :nth-last-of-type CSS pseudo-class matches an element that has an+b-1 siblings with the same element name after it in the document tree, for a given positive or zero value for n, and has a parent element.

See : for a more thorough description of the syntax of its argument.

Syntax

element:nth-last-of-type(an + b) {}

]]> :not(X), is a functional notation taking a simple selector X as an argument. It matches an element that is not represented by the argument. X must not contain another negation selector, or any pseudo-elements.]]>