CSS reference - CSS

Basic rule syntax

Style rule syntax

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

Where:

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.

-

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

x
:xr-overlay
xywh()

Y

y

Z

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.

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

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: 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.