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CSS reference

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Use this CSS reference to browse an alphabetical index of all of the standard CSS properties, pseudo-classes, pseudo-elements, data types, functional notations and at-rules. You can also browse key CSS concepts and a list of selectors organized by type. Also included is a brief DOM-CSS / CSSOM reference.

Basic rule syntax

Style rule syntax

plain
style-rule ::=
    selectors-list {
      properties-list
    }

Where:

plain
selectors-list ::=
    selector[:pseudo-class] [::pseudo-element]
    [, selectors-list]

properties-list ::=
    [property : value] [; properties-list]

See the index of selectors, pseudo-classes, and pseudo-elements below. The syntax for each specified value depends on the data type defined for each specified property.

Style rule examples

css
strong {
  color: red;
}

div.menu-bar li:hover > ul {
  display: block;
}

For a beginner-level introduction to the syntax of selectors, see our guide on CSS Selectors. Be aware that any syntax error in a rule definition invalidates the entire rule. Invalid rules are ignored by the browser. Note that CSS rule definitions are entirely (Unicode) text-based, whereas DOM-CSS / CSSOM (the rule management system) is object-based.

At-rule syntax

As the structure of at-rules varies widely, please see At-rule to find the syntax of the specific one you want.

Index

[!NOTE] This index does not include SVG-exclusive presentation attributes, which can be used as CSS properties on SVG elements.

[!NOTE] The property names in this index do not include the JavaScript names which do differ from the CSS standard names.

{{CSS_Ref}}

Selectors

The following are the various selectors, which allow styles to be conditional based on various features of elements within the DOM.

Basic selectors

Basic selectors are fundamental selectors; these are the most basic selectors that are frequently combined to create other, more complex selectors.

Grouping selectors

  • Selector list A, B
    • : Specifies that both A and B elements are selected. This is a grouping method to select several matching elements.

Combinators

Combinators are selectors that establish a relationship between two or more simple selectors, such as "A is a child of B" or "A is adjacent to B", creating a complex selector.

  • Next-sibling combinator A + B
    • : Specifies that the elements selected by both A and B have the same parent and that the element selected by B immediately follows the element selected by A horizontally.
  • Subsequent-sibling combinator A ~ B
    • : Specifies that the elements selected by both A and B share the same parent and that the element selected by A comes before—but not necessarily immediately before—the element selected by B.
  • Child combinator A > B
    • : Specifies that the element selected by B is the direct child of the element selected by A.
  • Descendant combinator A B
    • : Specifies that the element selected by B is a descendant of the element selected by A, but is not necessarily a direct child.
  • Column combinator A || B {{Experimental_Inline}}
    • : Specifies that the element selected by B is located within the table column specified by A. Elements which span multiple columns are considered to be a member of all of those columns.

Pseudo

  • Pseudo classes :
    • : Specifies a special state of the selected element(s).
  • Pseudo elements ::
    • : Represents entities that are not included in HTML.

[!CALLOUT]

See also selectors in the Selectors specification and the pseudo-element specification.

Concepts

Syntax and semantics

Values

Layout

DOM-CSS / CSSOM

Major object types

  • {{DOMxRef("Document.styleSheets")}}
  • {{DOMxRef("HTMLElement.style")}}
  • {{DOMxRef("Element.className")}}
  • {{DOMxRef("Element.classList")}}
  • {{DOMxRef("StyleSheetList")}}
  • {{DOMxRef("CSSRuleList")}}
  • {{DOMxRef("CSSRule")}}
  • {{DOMxRef("CSSStyleRule")}}
  • {{DOMxRef("CSSStyleDeclaration")}}

Important methods

  • {{DOMxRef("CSSStyleSheet.insertRule()")}}
  • {{DOMxRef("CSSStyleSheet.deleteRule()")}}

See also