CSS outline-offset

<!doctype html>
<title>Example</title>
<style>
div.color {
  width: 100px;
  height: 100px;
  outline-width: 5px;
  outline-style: solid;
  outline-color: limegreen;
  outline-offset: 10px;
  border: 1px solid black;
  margin: 20px;
  }
</style>
<div class="color">
  Green outline, black border. Outline-offset.
</div>

The CSS outline-offset property allows you to specify an offset between a box and its outline.

By default, outlines are drawn just outside the border edge. By using outline-offset, you can draw it beyond the border edge.

Syntax

Possible Values

The possible values for this property are:

<length>: Specifies the offset using a fixed length, for example, 10px or 1em.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial: Represents the value specified as the property's initial value.
inherit: Represents the computed value of the property on the element's parent.
unset: This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

Basic Property Information

Initial Value: 0
Applies To: All elements
Inherited?: No
Media: Visual
Animatable: Yes (see example)

Example Code

Basic CSS

Working Example within an HTML Document

Try it

CSS Specifications

The outline-offset property is defined in CSS Basic User Interface Module Level 3 (CSS3 UI) (W3C Candidate Recommendation, 7 July 2015).

Vendor Prefixes

For maximum browser compatibility many web developers add browser-specific properties by using extensions such as -webkit- for Safari, Google Chrome, and Opera (newer versions), -ms- for Internet Explorer, -moz- for Firefox, -o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.

This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.

The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.

Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.

You can also use Autoprefixer with preprocessors such as Less and Sass.

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