CSS Masking

With CSS masking you create a mask layer to place over an element to partially or fully hide portions of the element.

The CSS mask-image Property

The CSS mask-image property specifies a mask layer image.

The mask layer image can be a PNG image, an SVG image, a CSS gradient, or an SVG <mask> element.

Browser Support

Note: Most browsers only have partial support for CSS masking. You will need to use the -webkit- prefix in addition to the standard property in most browsers.

The numbers in the table below specify the first browser version that fully supports the property. Numbers followed by -webkit- specify the first version that worked with a prefix.

Property
mask-image	4.0 -webkit-	79.0 -webkit-	53.0	4.0 -webkit-	15.0 -webkit-

Use an Image as the Mask Layer

To use a PNG or an SVG image as the mask layer, use a url() value to pass in the mask layer image.

The mask image needs to have a transparent or semi-transparent area. Black indicates fully transparent.

Here is the mask image (a PNG image) we will use:

Here is an image from Cinque Terre, in Italy:

Now, we apply the mask image (the PNG image above) as the mask layer for the image from Cinque Terre, Italy:

Example

Here is the source code:

.mask1 {
-webkit-mask-image: url(w3logo.png);
mask-image: url(w3logo.png);
-webkit-mask-repeat: no-repeat;
mask-repeat: no-repeat;
}

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Example Explained

The mask-image property specifies the image to be used as a mask layer for an element.

The mask-repeat property specifies if or how a mask image will be repeated. The no-repeat value indicates that the mask image will not be repeated (the mask image will only be shown once).

Another Example

If we omit the mask-repeat property, the mask image will be repeated all over the image from Cinque Terre, Italy:

Example

Here is the source code:

.mask1 {
-webkit-mask-image: url(w3logo.png);
mask-image: url(w3logo.png);
}

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Use Gradients as the Mask Layer

CSS linear and radial gradients can also be used as mask images.

Linear Gradient Examples

Here, we use a linear-gradient as the mask layer for our image. This linear gradient goes from top (black) to bottom (transparent):

Example

Use a linear gradient as a mask layer:

.mask1 {
-webkit-mask-image: linear-gradient(black, transparent);
mask-image: linear-gradient(black, transparent);
}

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Here, we use a linear-gradient along with text masking as the mask layer for our image:

The Cinque Terre is a coastal area within Liguria, in the northwest of Italy. It lies in the west of La Spezia Province, and comprises five villages: Monterosso al Mare, Vernazza, Corniglia, Manarola, and Riomaggiore.

Example

Use a linear gradient along with text masking as a mask layer:

.mask1 {
max-width: 600px;
height: 350px;
overflow-y: scroll;
background: url(img_5terre.jpg) no-repeat;
-webkit-mask-image: linear-gradient(black, transparent);
mask-image: linear-gradient (black, transparent);
}

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Radial Gradient Examples

Here, we use a radial-gradient (shaped as a circle) as the mask layer for our image:

Example

Use a radial gradient as a mask layer (a circle):

.mask2 {
-webkit-mask-image: radial-gradient(circle, black 50%, rgba(0, 0, 0, 0.5) 50%);
mask-image: radial-gradient(circle, black 50%, rgba(0, 0, 0, 0.5) 50%);
}

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Here, we use a radial-gradient (shaped as an ellipse) as the mask layer for our image:

Example

Use another radial gradient as a mask layer (an ellipse):

.mask3 {
-webkit-mask-image: radial-gradient(ellipse, black 50%, rgba(0, 0, 0, 0.5) 50%);
mask-image: radial-gradient(ellipse, black 50%, rgba(0, 0, 0, 0.5));
}

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Use SVG as the Mask Layer

The SVG <mask> element can be used inside an SVG graphic to create masking effects.

Here, we use the SVG <mask> element to create different mask layers for our image:

Example

An SVG mask layer (formed as a triangle):

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Example

An SVG mask layer (formed as a star):

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Example

An SVG mask layer (formed as circles):

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CSS Masking Properties

The following table lists all the CSS masking properties:

Property	Description
mask-image	Specifies an image to be used as a mask layer for an element
mask-mode	Specifies whether the mask layer image is treated as a luminance mask or as an alpha mask
mask-origin	Specifies the origin position (the mask position area) of a mask layer image
mask-position	Sets the starting position of a mask layer image (relative to the mask position area)
mask-repeat	Specifies how the mask layer image is repeated
mask-size	Specifies the size of a mask layer image

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