outline

Summary

The CSS outline property is a shorthand property for setting one or more of the individual outline properties outline-style, outline-width and outline-color in a single rule. In most cases the use of this shortcut is preferable and more convenient.

Outlines differ from borders in the following ways:

  • Outlines do not take up space, they are drawn above the content.
  • Outlines may be non-rectangular. They are rectangular in Gecko/Firefox. But e.g. Opera draws a non-rectangular shape around a construct like this:
    TEXTTEXTTEXT
  • Initial value the concatenation of the initial values of its longhand properties:
    • outline-color: invert, for browsers supporting it, currentColor for the other
    • outline-style: none
    • outline-width: medium
  • Applies to all elements
  • Inherited no
  • Media visual, interactive
  • Computed value as each of the properties of the shorthand:
    • outline-color: For the keyword invert, the computed value is invert. For the color value, if the value is translucent, the computed value will be the rgba() corresponding one. If it isn't, it will be the rgb() corresponding one. The transparent keyword maps to rgb(0,0,0).
    • outline-width: an absolute length; if the keyword none is specified, the computed value is 0
    • outline-style: as specified
  • Animatable as each of the properties of the shorthand:
    • outline-color: yes, as a color
    • outline-width: yes, as a length
    • outline-style: no
  • Canonical order order of appearance in the formal grammar of the values

Syntax

Formal syntax: <'outline-color'> || <'outline-style'> || <'outline-width'>

Values

One, two or three values, given in arbitrary order:

<'outline-width'>
See outline-width.
<'outline-style'>
See outline-style.
<'outline-color'>
Since Gecko 1.9 (Firefox 3), the value of the element's color property (foreground color) is used. See outline-color.

Examples

outline: solid; | outline: dashed red; | outline: dotted 1px; | outline: ridge thick violet; | outline: custom 5px;
/* two identical declarations */

:link:hover { outline: 1px solid #000; }
:link:hover { outline: solid black 1px; }

Specifications

Specification Status Comment
CSS Basic User Interface Module Level 3 Working Draft No change.
CSS Level 2 (Revision 1) Recommendation  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 1.5 (1.8) 8.0 7.0 1.2 (125)
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 1.0 1.0 (1.8) 8.0 6.0 3.1

In browsers previous to Gecko 1.8 (Firefox 1.5) a similar effect can be achieved using Mozilla CSS Extension -moz-outline.

See also

Document Tags and Contributors

Last updated by: kscarfone,
Hide Sidebar