Pseudo-classes - CSS: Cascading Style Sheets 编辑

A CSS pseudo-class is a keyword added to a selector that specifies a special state of the selected element(s). For example, :hover can be used to change a button's color when the user's pointer hovers over it.

/* Any button over which the user's pointer is hovering */
button:hover {
  color: blue;
}

Pseudo-classes let you apply a style to an element not only in relation to the content of the document tree, but also in relation to external factors like the history of the navigator (:visited, for example), the status of its content (like :checked on certain form elements), or the position of the mouse (like :hover, which lets you know if the mouse is over an element or not).

Note: In contrast to pseudo-classes, pseudo-elements can be used to style a specific part of an element.

Linguistic pseudo-classes

These pseudo-classes reflect the document language, and enable the selection of elements based on language or script direction.

:dir

The directionality pseudo-class selects an element based on its directionality as determined by the document language.

:lang

Select an element based on its content language.

Location pseudo-classes

These pseudo-classes relate to links, and to targeted elements within the current document.

:any-link

Matches an element if the element would match either :link or :visited.

:link

Matches links that have not yet been visited.

:visited

Matches links that have been visited.

:local-link

Matches links whose absolute URL is the same as the target URL, for example anchor links to the same page.

:target

Matches the element which is the target of the document URL.

:target-within

Matches elements which are the target of the document URL, but also elements which have a descendant which is the target of the document URL.

:scope

Represents elements that are a reference point for selectors to match against.

User action pseudo-classes

These pseudo-classes require some interaction by the user in order for them to apply, such as holding a mouse pointer over an element.

:hover

Matches when a user designates an item with a pointing device, for example holding the mouse pointer over it.

:active

Matches when an item is being activated by the user, for example clicked on.

:focus

Matches when an element has focus.

:focus-visible

Matches when an element has focus and the user agent identifies that the element should be visibly focused. 

:focus-within

Matches an element to which :focus applies, plus any element that has a descendant to which :focus applies.

Time-dimensional pseudo-classes

These pseudo-classes apply when viewing something which has timing, such as a WebVTT caption track.

:current

Represents the element or ancestor of the element that is being displayed.

:past

Represents an element that occurs entirely before the :current element.

:future

Represents an element that occurs entirely after the :current element.

Resource state pseudo-classes

These pseudo-classes apply to media that is capable of being in a state where it would be described as playing, such as a video.

:playing

Represents a media element that is capable of playing when that element is playing.

:paused

Represents a media element that is capable of playing when that element is paused.

The input pseudo-classes

These pseudo-classes relate to form elements, and enable selecting elements based on HTML attributes and the state that the field is in before and after interaction.

:enabled

Represents a user interface element that is in an enabled state.

:disabled

Represents a user interface element that is in a disabled state.

:read-only

Represents any element that cannot be changed by the user.

:read-write

Represents any element that is user-editable.

:placeholder-shown

Matches an input element that is displaying placeholder text, for example from the HTML5 placeholder attribute.

:default

Matches one or more UI elements that are the default among a set of elements.

:checked

Matches when elements such as checkboxes and radiobuttons are toggled on.

:indeterminate

Matches when UI elements are in an undeterminate state.

:blank

Matches a user-input element which is empty, containing an empty string or other null input.

:valid

Matches an element with valid contents. For example an input element with type 'email' which contains a validly formed email address.

:invalid

Matches an element with invalid contents. For example an input element with type 'email' with a name entered.

:in-range

Applies to elements with range limitations, for example a slider control, when the selected value is in the allowed range.

:out-of-range

Applies to elements with range limitations, for example a slider control, when the selected value is outside the allowed range.

:required

Matches when a form element is required.

:optional

Matches when a form element is optional.

:user-invalid

Represents an element with incorrect input, but only when the user has interacted with it.

Tree-structural pseudo-classes

These pseudo-classes relate to the location of an element within the document tree.

:root

Represents an element that is the root of the document. In HTML this is usually the <html> element.

:empty

Represents an element with no children other than white-space characters.

:nth-child

Uses An+B notation to select elements from a list of sibling elements.

:nth-last-child

Uses An+B notation to select elements from a list of sibling elements, counting backwards from the end of the list.

:first-child

Matches an element that is the first of its siblings.

:last-child

Matches an element that is the last of its siblings.

:only-child

Matches an element that has no siblings. For example a list item with no other list items in that list.

:nth-of-type

Uses An+B notation to select elements from a list of sibling elements that match a certain type from a list of sibling elements.

:nth-last-of-type

Uses An+B notation to select elements from a list of sibling elements that match a certain type from a list of sibling elements counting backards from the end of the list.

:first-of-type

Matches an element that is the first of its siblings, and also matches a certain type selector.

:last-of-type

Matches an element that is the last of its siblings, and also matches a certain type selector.

:only-of-type

Matches an element that has no siblings of the chosen type selector.

Syntax

selector:pseudo-class {
  property: value;
}

Like regular classes, you can chain together as many pseudo-classes as you want in a selector.

Alphabetical index

Pseudo-classes defined by a set of CSS specifications include the following:

• :active
• :any-link 

• :blank 

• :checked
• :current 

• :default
• :defined
• :dir() 
• :disabled

• :empty
• :enabled

• :first
• :first-child
• :first-of-type
• :fullscreen 
• :future 
• :focus
• :focus-visible 
• :focus-within

• :has() 
• :host
• :host()
• :host-context() 
• :hover

• :indeterminate
• :in-range
• :invalid
• :is() 

• :lang()
• :last-child
• :last-of-type
• :left
• :link
• :local-link 

• :not()
• :nth-child()
• :nth-col() 
• :nth-last-child()
• :nth-last-col() 
• :nth-last-of-type()
• :nth-of-type()

• :only-child
• :only-of-type
• :optional
• :out-of-range

• :past 
• :picture-in-picture
• :placeholder-shown 
• :paused
• :playing

• :read-only
• :read-write
• :required
• :right
• :root

• :scope
• :state() 

• :target
• :target-within 

• :user-invalid 

• :valid
• :visited

• :where() 

Specifications

See also

• Pseudo-elements