`mask-border-source` CSS property

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

See full compatibility

The mask-border-source CSS property sets the source image used to create an element's mask border.

The mask-border-slice property is used to divide the source image into regions, which are then dynamically applied to the final mask border.

Syntax

css

/* Keyword value */
mask-border-source: none;

/* <image> values */
mask-border-source: url("image.jpg");
mask-border-source: linear-gradient(to top, red, yellow);

/* Global values */
mask-border-source: inherit;
mask-border-source: initial;
mask-border-source: revert;
mask-border-source: revert-layer;
mask-border-source: unset;

Values

none: No mask border is used.
<image>: Image reference to use for the mask border.

Formal definition

Initial value	`none`
Applies to	all elements; In SVG, it applies to container elements excluding the `<defs>` element and all graphics elements
Inherited	no
Computed value	as specified, but with `<url>` values made absolute
Animation type	discrete

Formal syntax

mask-border-source = 
  <'border-image-source'>  

<border-image-source> = 
  none     |
  <image>  

<image> = 
  <url>           |
  <image()>       |
  <image-set()>   |
  <cross-fade()>  |
  <element()>     |
  <gradient>      

<image()> = 
  image( <image-tags>? [ <image-src>? , <color>? ]! )  

<image-set()> = 
  image-set( <image-set-option># )  

<cross-fade()> = 
  cross-fade( <cf-image># )  

<element()> = 
  element( <id-selector> )  

<image-tags> = 
  ltr  |
  rtl  

<image-src> = 
  <url>     |
  <string>  

<image-set-option> = 
  [ <image> | <string> ] [ <resolution> || type( <string> ) ]?  

<cf-image> = 
  [ <image> | <color> ]  &&
  <percentage [0,100]>?  

<id-selector> = 
  <hash-token>

Examples

Basic usage

This property doesn't appear to be supported anywhere yet. When it eventually starts to be supported, it will serve to define the source of the border mask.

css

mask-border-source: url("image.jpg");

Chromium-based browsers support an outdated version of this property — mask-box-image-source — with a prefix:

css

-webkit-mask-box-image-source: url("image.jpg");

Note: The mask-border page features a working example (using the out-of-date prefixed border mask properties supported in Chromium), so you can get an idea of the effect.

Specifications

Specification
CSS Masking Module Level 1 # the-mask-border-source

Browser compatibility

	desktop					mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS
`mask-border-source`	Chrome – Full support Chrome 1 (Release date: 2008-12-11) altname altname Alternate name: -webkit-mask-box-image-source	Edge – Full support Edge 79 (Release date: 2020-01-15) altname altname Alternate name: -webkit-mask-box-image-source	Firefox – No support Firefox footnote footnote See bug 877294	Opera – Full support Opera 15 (Release date: 2013-07-02) altname altname Alternate name: -webkit-mask-box-image-source	Safari – Full support Safari 3.1 (Release date: 2008-03-18) altname altname Alternate name: -webkit-mask-box-image-source Safari – Full support Safari 17.2 (Release date: 2023-12-11) footnote Full support	Chrome Android – Full support Chrome Android 18 (Release date: 2012-06-27) altname altname Alternate name: -webkit-mask-box-image-source	Firefox for Android – No support Firefox for Android footnote footnote See bug 877294	Opera Android – Full support Opera Android 14 (Release date: 2013-05-21) altname altname Alternate name: -webkit-mask-box-image-source	Safari on iOS – Full support Safari on iOS 2 (Release date: 2008-07-11) altname altname Alternate name: -webkit-mask-box-image-source Safari on iOS – Full support Safari on iOS 17.2 (Release date: 2023-12-11) footnote Full support	Samsung Internet – Full support Samsung Internet 1 (Release date: 2013-04-27) altname altname Alternate name: -webkit-mask-box-image-source	WebView Android – Full support WebView Android 4.4 (Release date: 2013-12-09) altname altname Alternate name: -webkit-mask-box-image-source	WebView on iOS – Full support WebView on iOS 2 (Release date: 2008-07-11) altname altname Alternate name: -webkit-mask-box-image-source WebView on iOS – Full support WebView on iOS 17.2 (Release date: 2023-12-11) footnote Full support

Tip: you can click/tap on a cell for more information.

Full support: Full support
No support: No support
: See implementation notes.
: Uses a non-standard name
: Has more compatibility info.

mask-border-source CSS property

Legend

`mask-border-source` CSS property