The mask-type CSS property determines whether the mask defined by an SVG <mask> element is used as a luminance or an alpha mask. It applies to the <mask> element itself.

/* Keyword values */
mask-type: luminance;
mask-type: alpha;

/* Global values */
mask-type: inherit;
mask-type: initial;
mask-type: unset;

This property may be overridden by the mask-mode property, which has the same effect but applies to the element where the mask is used. Alpha masks will generally be faster to render.

Initial valueluminance
Applies to<mask> elements
Computed valueas specified
Animation typediscrete
Canonical orderper grammar


The mask-type property is specified as one of the keyword values listed below.


Is a keyword indicating that the associated mask image is a luminance mask, i.e., that its relative luminance values must be used when applying it.
Is a keyword indicating that the associated mask image is an alpha mask, i.e., that its alpha channel values must be used when applying it.

Formal syntax

luminance | alpha


Let's apply the following rectangle as a mask:

<rect x="10" y="10" width="80" height="80"
    fill="red" fill-opacity="0.7" />
which leads to the following square:

to this box:

The result, if your browser supports the property, with different value of mask-type applied to the <mask> element are these two different squares:

mask-type: alpha; mask-type: luminance;


Specification Status Comment
CSS Masking Module Level 1
The definition of 'mask-type' in that specification.
Candidate Recommendation Initial definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support24 ?


20 — 521

? ? ?
Applies to HTML elements No ?20 No No ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support ? ? ?


20 — 521

? ? ?
Applies to HTML elements ? ? ?20 ? ? No

1. From version 20 until version 52 (exclusive): this feature is behind the layout.css.masking.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.

See also

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Last updated by: mfluehr,