CSS reference

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

Basic rule syntax

Style rule syntax

selectorlist {
  property: value;
  [more property:value; pairs]
}

... where selectorlist is: selector[:pseudo-class] [::pseudo-element] [, more selectorlists]

See selector, pseudo-class, pseudo-element lists below.

Style rule examples

strong {
  color: red;
}

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

For a beginner-level introduction to the syntax of CSS selectors, please see this tutorial. Be aware that any CSS syntax error in a rule definition invalidates the entire rule. Invalid rules are ignored by the browser. Note that CSS rule definitions are entirely (ASCII) 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.

Keyword index

The property names in this index do not include the JavaScript names where they differ from the CSS standard names.

Selectors

Basic selectors

• Type selector elementname
• Class selector .classname
• ID selector #idname
• Universal selector *, ns|*, *|*, |*
• Attribute selector [attr=value]

Combinators

• Adjacent sibling combinator A + B
• General sibling combinator A ~ B
• Child combinator A > B
• Descendant combinator A B

Pseudo-classes

Pseudo-elements

Concepts

Syntax and semantics

• CSS syntax
• At-rules
• Cascade
• Comments
• Descriptor
• Inheritance
• Shorthand properties
• Specificity
• Value definition syntax

Values

• Actual value
• Computed value
• Initial value
• Resolved value
• Specified value
• Used value

Layout

• Block formatting context
• Box model
• Containing block
• Layout mode
• Margin collapsing
• Replaced elements
• Stacking context
• Visual formatting model

DOM-CSS / CSSOM

Major object types

• document.styleSheets
• styleSheets[i].cssRules
• cssRules[i].cssText (selector & style)
• cssRules[i].selectorText
• elem.style
• elem.style.cssText (just style)
• elem.className
• elem.classList

Important methods

• CSSStyleSheet.insertRule
• CSSStyleSheet.deleteRule

See also

• Mozilla CSS extensions (prefixed with -moz)
• WebKit CSS extensions (mostly prefixed with -webkit)
• Microsoft CSS extensions (prefixed with -ms)