Pseudo-classes

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

css

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

A pseudo-class consists of a colon (:) followed by the pseudo-class name (e.g., :hover). A functional pseudo-class also contains a pair of parentheses to define the arguments (e.g., :dir()). The element that a pseudo-class is attached to is defined as an anchor element (e.g., button in case button:hover).

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.

Element display state pseudo-classes

These pseudo-classes enable the selection of elements based on their display states.

:fullscreen: Matches an element that is currently in fullscreen mode.
:modal: Matches an element that is in a state in which it excludes all interaction with elements outside it until the interaction has been dismissed.
:picture-in-picture: Matches an element that is currently in picture-in-picture mode.

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.

:autofill: Matches when an <input> has been autofilled by the browser.
: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, it will match the placeholder attribute in the <input> and <textarea> elements.
:default: Matches one or more UI elements that are the default among a set of elements.
:checked: Matches when elements such as checkboxes and radio buttons are toggled on.
:indeterminate: Matches UI elements when they are in an indeterminate 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 the type 'email' that contains a validly formed email address or an empty value if the control is not required.
: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.

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.

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.

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.

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 backwards 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.

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, such as holding the mouse pointer over the item.
:active: Matches when an item is being activated by the user. For example, when the item is 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.

Functional pseudo-classes

These pseudo-classes accept a selector list or forgiving selector list as a parameter.

:is(): The matches-any pseudo-class matches any element that matches any of the selectors in the list provided. The list is forgiving.
:not(): The negation, or matches-none, pseudo-class represents any element that is not represented by its argument.
:where(): The specificity-adjustment pseudo-class matches any element that matches any of the selectors in the list provided without adding any specificity weight. The list is forgiving.
:has(): The relational pseudo-class represents an element if any of the relative selectors match when anchored against the attached element.

Syntax

css

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:

:blank Experimental

:checked
:current Experimental

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

:modal

:scope
:state() Experimental

:target
:target-within Experimental

:user-invalid Experimental

:where()

Specifications

Specification
HTML Standard # pseudo-classes
Selectors Level 4
CSS Basic User Interface Module Level 4

Docs

Docs4dev

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