The outline-width CSS property sets the width (thickness) of an element's outline. An outline is a line that is drawn around an element, outside the border.

It is often more convenient to use the shorthand property outline when defining the appearance of an outline.

Syntax

/* Keyword values */
outline-width: thin;
outline-width: medium;
outline-width: thick;

/* <length> values */
outline-width: 1px;
outline-width: 0.1em;

/* Global values */
outline-width: inherit;

The outline-width property is specified as any one of the values listed below.

Values

<length>
The width of the outline specified as a <length>.
thin
Depends on the user agent. Typically equivalent to 1px in desktop browsers (including Firefox).
medium
Depends on the user agent. Typically equivalent to 3px in desktop browsers (including Firefox).
thick
Depends on the user agent. Typically equivalent to 5px in desktop browsers (including Firefox).

Formal syntax

<br-width>

where
<br-width> = <length> | thin | medium | thick

Examples

HTML

<span id="thin">thin</span>
<span id="medium">medium</span>
<span id="thick">thick</span>
<span id="twopixels">2px</span>
<span id="oneex">1ex</span>
<span id="em">1.2em</span>

CSS

span {
  outline-style: solid;
  display: inline-block;
  margin: 20px;
}

#thin {
  outline-width: thin;
}

#medium {
  outline-width: medium;
}

#thick {
  outline-width: thick;
}

#twopixels {
  outline-width: 2px;
}

#oneex {
  outline-width: 1ex;
}

#em {
  outline-width: 1.2em;
}

Specifications

Specification Status Comment
CSS Basic User Interface Module Level 3
The definition of 'outline-width' in that specification.
Proposed Recommendation No change.
CSS Transitions
The definition of 'outline-width' in that specification.
Working Draft Defines outline-width as animatable.
CSS Level 2 (Revision 1)
The definition of 'outline-width' in that specification.
Recommendation Initial definition.

Initial valuemedium
Applies toall elements
Inheritedno
Mediavisual, interactive
Computed valuean absolute length; if the keyword none is specified, the computed value is 0
Animation typea length
Canonical orderthe unique non-ambiguous order defined by the formal grammar

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 Yes

1.5

1 —? -moz-

871.2
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support ? ? Yes ? ? ? ?

Document Tags and Contributors

 Last updated by: wbamberg,