mask

Baseline 2023

Newly available

Since December 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The mask CSS shorthand property hides an element (partially or fully) by masking or clipping the image at specific points.

Note: As well as the properties listed below, the mask shorthand also resets mask-border to its initial value. It is therefore recommended to use the mask shorthand rather than other shorthands or the individual properties to override any mask settings earlier in the cascade. This will ensure that mask-border has also been reset to allow the new styles to take effect.

Constituent properties

This property is a shorthand for the following CSS properties:

Syntax

/* Keyword values */
mask: none;

/* Image values */
mask: url(mask.png); /* Pixel image used as mask */
mask: url(masks.svg#star); /* Element within SVG graphic used as mask */

/* Combined values */
mask: url(masks.svg#star) luminance; /* Element within SVG graphic used as luminance mask */
mask: url(masks.svg#star) 40px 20px; /* Element within SVG graphic used as mask positioned 40px from the top and 20px from the left */
mask: url(masks.svg#star) 0 0/50px 50px; /* Element within SVG graphic used as mask with a width and height of 50px */
mask: url(masks.svg#star) repeat-x; /* Element within SVG graphic used as horizontally repeated mask */
mask: url(masks.svg#star) stroke-box; /* Element within SVG graphic used as mask extending to the box enclosed by the stroke */
mask: url(masks.svg#star) exclude; /* Element within SVG graphic used as mask and combined with background using non-overlapping parts */

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

/* Multiple masks */
mask:
  url(masks.svg#star) left / 16px repeat-y,
  /* Element within SVG graphic is used as a mask on the left-hand side with a width of 16px */
    url(masks.svg#circle) right / 16px repeat-y; /* Element within SVG graphic is used as a mask on the right-hand side with a width of 16px */

Values

<mask-reference>: Sets the mask image source. See mask-image.
<masking-mode>: Sets the masking mode of the mask image. See mask-mode.
<position>: Sets the position of the mask image. See mask-position.
<bg-size>: Sets the size of the mask image. See mask-size.
<repeat-style>: Sets the repetition of the mask image. See mask-repeat.
<geometry-box>: If only one <geometry-box> value is given, it sets both mask-origin and mask-clip. If two <geometry-box> values are present, then the first sets mask-origin and the second sets mask-clip.
<geometry-box> | no-clip: Sets the area that is affected by the mask image. See mask-clip.
<compositing-operator>: Sets the compositing operation used on the current mask layer. See mask-composite.

Formal definition

Initial value	as each of the properties of the shorthand: `mask-image`: `none` `mask-mode`: `match-source` `mask-repeat`: `repeat` `mask-position`: `0% 0%` `mask-clip`: `border-box` `mask-origin`: `border-box` `mask-size`: `auto` `mask-composite`: `add`
Applies to	all elements; In SVG, it applies to container elements excluding the `<defs>` element and all graphics elements
Inherited	no
Percentages	as each of the properties of the shorthand: `mask-position`: refer to size of mask painting area minus size of mask layer image (see the text for `background-position`)
Computed value	as each of the properties of the shorthand: `mask-image`: as specified, but with `<url>` values made absolute `mask-mode`: as specified `mask-repeat`: Consists of two keywords, one per dimension `mask-position`: Consists of two keywords representing the origin and two offsets from that origin, each given as an absolute length (if given a <length>), otherwise as a percentage. `mask-clip`: as specified `mask-origin`: as specified `mask-size`: as specified, but with relative lengths converted into absolute lengths `mask-composite`: as specified
Animation type	as each of the properties of the shorthand: `mask-image`: discrete `mask-mode`: discrete `mask-repeat`: discrete `mask-position`: a repeatable list `mask-clip`: discrete `mask-origin`: discrete `mask-size`: a repeatable list `mask-composite`: discrete
Creates stacking context	yes

Formal syntax

mask = 
  <mask-layer>#  

<mask-layer> = 
  <mask-reference>              ||
  <position> [ / <bg-size> ]?   ||
  <repeat-style>                ||
  <geometry-box>                ||
  [ <geometry-box> | no-clip ]  ||
  <compositing-operator>        ||
  <masking-mode>                

<mask-reference> = 
  none           |
  <image>        |
  <mask-source>  

<position> = 
  [ left | center | right | top | bottom | <length-percentage> ]  |
  [ left | center | right ] && [ top | center | bottom ]  |
  [ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ]  |
  [ [ left | right ] <length-percentage> ] && [ [ top | bottom ] <length-percentage> ]  

<bg-size> = 
  [ <length-percentage [0,∞]> | auto ]{1,2}  |
  cover                                      |
  contain                                    

<repeat-style> = 
  repeat-x                                     |
  repeat-y                                     |
  [ repeat | space | round | no-repeat ]{1,2}  

<geometry-box> = 
  <shape-box>  |
  fill-box     |
  stroke-box   |
  view-box     

<compositing-operator> = 
  add        |
  subtract   |
  intersect  |
  exclude    

<masking-mode> = 
  alpha         |
  luminance     |
  match-source  

<image> = 
  <url>       |
  <gradient>  

<mask-source> = 
  <url>  

<length-percentage> = 
  <length>      |
  <percentage>  

<shape-box> = 
  <visual-box>  |
  margin-box    

<url> = 
  <url()>  |
  <src()>  

<visual-box> = 
  content-box  |
  padding-box  |
  border-box   

<url()> = 
  url( <string> <url-modifier>* )  |
  <url-token>                      

<src()> = 
  src( <string> <url-modifier>* )

Examples

Masking an image

.target {
  mask: url(#c1) luminance;
}

.another-target {
  mask: url(resources.svg#c1) 50px 30px/10px 10px repeat-x exclude;
}

Specifications

Specification
CSS Masking Module Level 1 # the-mask

Browser compatibility

	Desktop					Mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android
`mask`	120 1 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 1–120 While the property is recognized, values applied to it don't have any effect.	120 79 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 79–120 While the property is recognized, values applied to it don't have any effect. 12–79	53 2–53 Only supports `mask: url(file.svg#mask_id)` or `mask: url(#mask_id)`, where the URL is a reference to an SVG `<mask>` element.	106 15 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 15–106 While the property is recognized, values applied to it don't have any effect.	15.4 3.1 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 3.1–15.4 While the property is recognized, values applied to it don't have any effect.	120 18 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 18–120 While the property is recognized, values applied to it don't have any effect.	53 4–53 Only supports `mask: url(file.svg#mask_id)` or `mask: url(#mask_id)`, where the URL is a reference to an SVG `<mask>` element.	80 14 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 14–80 While the property is recognized, values applied to it don't have any effect.	15.4 2 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 2–15.4 While the property is recognized, values applied to it don't have any effect.	25.0 1.0 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 1.0–25.0 While the property is recognized, values applied to it don't have any effect.	120 2 The prefixed property can be used with SVG and HTML with a slightly different syntax, which allows setting the non-standard `-webkit-mask-attachment` property. 2–120 While the property is recognized, values applied to it don't have any effect.