This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The mask-border
CSS shorthand property lets you create a mask along the edge of an element's border.
Constituent properties
This property is a shorthand for the following CSS properties:
mask-border-mode
mask-border-outset
mask-border-repeat
mask-border-slice
mask-border-source
mask-border-width
Syntax
/* source | slice */ mask-border: url('border-mask.png') 25; /* source | slice | repeat */ mask-border: url('border-mask.png') 25 space; /* source | slice | width */ mask-border: url('border-mask.png') 25 / 35px; /* source | slice | width | outset | repeat | mode */ mask-border: url('border-mask.png') 25 / 35px / 12px space alpha;
Values
<'mask-border-source'>
- The source image. See
mask-border-source
. <'mask-border-slice'>
- The dimensions for slicing the source image into regions. Up to four values may be specified. See
mask-border-slice
. <'mask-border-width'>
- The width of the border mask. Up to four values may be specified. See
mask-border-width
. <'mask-border-outset'>
- The distance of the border mask from the element's outside edge. Up to four values may be specified. See
mask-border-outset
. <'mask-border-repeat'>
- Defines how the edge regions of the source image are adjusted to fit the dimensions of the border mask. Up to two values may be specified. See
mask-border-repeat
. <'mask-border-mode'>
- Defines whether the source image is treated as a luminance mask or alpha mask. See
mask-border-mode
.
Formal definition
Initial value | as each of the properties of the shorthand:
|
---|---|
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:
|
Computed value | as each of the properties of the shorthand:
|
Animation type | as each of the properties of the shorthand:
|
Creates stacking context | yes |
Formal syntax
<'mask-border-source'> | <'mask-border-slice'> [ / <'mask-border-width'>? [ / <'mask-border-outset'> ]? ]? | <'mask-border-repeat'> | <'mask-border-mode'>
Examples
Setting a bitmap-based mask border
In this example, we will mask an element's border with a diamond pattern. The source for the mask is a ".png" file of 90 by 90 pixels, with three diamonds going vertically and horizontally:
HTML
<div id="bitmap">This element is surrounded by a bitmap-based mask border! Pretty neat, isn't it?</div>
CSS
To match the size of a single diamond, we will use a value of 90 divided by 3, or 30
, for slicing the image into corner and edge regions. A repeat value of round
will make the mask slices fit evenly, i.e., without clipping or gaps.
div { width: 200px; background-color: lavender; border: 18px solid salmon; padding: 10px; /* Prefixed longhand properties currently supported in Chromium -webkit-mask-box-image-source: url(https://udn.realityripple.com/samples/2d/fd08a3134c.png); -webkit-mask-box-image-slice: 30 fill; -webkit-mask-box-image-width: 20px; -webkit-mask-box-image-repeat: round; -webkit-mask-box-image-outset: 1px; */ /* Prefixed shorthand property currently supported in Chromium */ -webkit-mask-box-image: url("https://udn.realityripple.com/samples/2d/fd08a3134c.png") /* source */ 30 fill / /* slice */ 20px / /* width */ 1px /* outset */ round; /* repeat */ /* Updated standard shorthand property, not supported anywhere yet */ mask-border: url("https://udn.realityripple.com/samples/2d/fd08a3134c.png") /* source */ 30 fill / /* slice */ 20px / /* width */ 1px /* outset */ round; /* repeat */ }
Result
Specifications
Specification | Status | Comment |
---|---|---|
CSS Masking Module Level 1 The definition of 'mask-border' in that specification. |
Candidate Recommendation | Initial definition |
Browser compatibility
TBD