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outline

The outline CSS shorthand property set all the outline properties in a single declaration.

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

/* style */
outline: solid;

/* color | style */
outline: #f66 dashed;

/* style | width */
outline: inset thick;

/* color | style | width */
outline: green solid 3px;

/* Global values */
outline: inherit;
outline: initial;
outline: unset;

The outline property may be specified using one, two, or three of the values listed below. The order of the values does not matter.

Note: The outline will be invisible for many elements if its style is not defined. This is because the style defaults to none. A notable exception is input elements, which are given default styling by browsers.

Values

<'outline-color'>
Sets the color of the outline. Defaults to currentcolor if absent. See outline-color.
<'outline-style'>
Sets the style of the outline. Defaults to none if absent. See outline-style.
<'outline-width'>
Sets the thickness of the outline. Defaults to medium if absent. See outline-width.

Description

Borders and outlines are very similar. However, outlines differ from borders in the following ways:

  • Outlines never take up space, as they are drawn outside of an element's content.
  • According to the spec, outlines don't have to be rectangular, although they usually are.

As with all shorthand properties, any omitted sub-values will be set to their initial value.

Accessibility concerns

Assigning outline a value of 0 or none will remove the browser's default focus style. If an element can be interacted with it must have a visible focus indicator. Provide obvious focus styling if the default focus style is removed.

Formal definition

Initial value as each of the properties of the shorthand:
Applies to all elements
Inherited no
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 rgba(0,0,0,0).
  • outline-width: an absolute length; if the keyword none is specified, the computed value is 0
  • outline-style: as specified
Animation type as each of the properties of the shorthand:

Formal syntax

[ <'outline-color'> || <'outline-style'> || <'outline-width'> ]

Examples

Using outline to set a focus style

HTML

<a href="#">This link has a special focus style.</a>

CSS

a {
  border: 1px solid;
  border-radius: 3px;
  display: inline-block;
  margin: 10px;
  padding: 5px;
}

a:focus {
  outline: 4px dotted #e73;
  outline-offset: 4px;
  background: #ffa;
}

Result

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
outline 1 12 1.5
1.5
Firefox includes absolutely positioned elements inside the outline (see bug 687311).
1 — 3.6
Prefixed
Prefixed Implemented with the vendor prefix: -moz-
8 7 1.2
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
outline 1 18 4 10.1 3.1 1.0

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/CSS/outline