outline-width

Summary

The outline-width CSS property is used to set the width of the outline of an element. An outline is a line that is drawn around elements, outside the border edge, to make the element stand out:

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;

Values

thin

Depends on the UA. Typically 1px in desktop browsers like Firefox.

medium

Depends on the UA. Typically 3px in desktop browsers like Firefox.

thick

Depends on the UA. Typically 5px in desktop browsers like Firefox.

<length>

See <length> values.

Formal syntax

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

Examples

HTML Content

<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="twoem">2em</span>

CSS Content

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;
}

#twoem {
  outline-width: 2em;
}

Specifications

Browser compatibility

[1] In browsers previous to Gecko 1.8 (Firefox 1.5) essentially the same effect can be achieved using Mozilla CSS Extension -moz-outline-width.