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

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
• Column 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-)