This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
Summary
The mask-position CSS property sets the initial position, relative to the mask position layer defined by mask-origin for each defined mask image.
| Initial value | center |
|---|---|
| Applies to | all elements; In SVG, it applies to container elements excluding the <defs> element and all graphics elements |
| Inherited | no |
| Percentages | refer to size of mask painting area minus size of mask layer image (see the text for background-position) |
| Media | visual |
| Computed value | 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. |
| Animation type | a repeatable list of , a simple list of , a length, percentage or calc(); |
| Canonical order | the unique non-ambiguous order defined by the formal grammar |
Syntax
/* Keyword values */ mask-position: top; mask-position: bottom; mask-position: left; mask-position: right; mask-position: center; /* values */ mask-position: 25% 75%; /* values */ mask-position: 0px 0px; mask-position: 1cm 2cm; mask-position: 10ch 8em; /* Multiple values */ mask-position: 0px 0px, center; /* Global values */ mask-position: inherit; mask-position: initial; mask-position: unset;
Values
<position>- Is a
<position>, that is one to four values representing a 2D position regarding the edges of the element's box. Relative or absolute offsets can be given. Note that the position can be set outside of the element's box.
Formal syntax
<position>#where
<position> = [[ left | center | right | top | bottom | <length-percentage> ] | [ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ] | [ center | [ left | right ] <length-percentage>? ] && [ center | [ top | bottom ] <length-percentage>? ]]where
<length-percentage> = <length> | <percentage>
Example
.exampleOne {
mask-image: url(mask.png);
mask-position: bottom right;
}
.exampleTwo {
mask-image: url(mask.png);
mask-position: 25%;
}
Specifications
| Specification | Status | Comment |
|---|---|---|
| CSS Masking Level 1 The definition of 'mask-position' in that specification. |
Candidate Recommendation | Initial definition |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | 1.0-webkit | No support[2] | ? | ? | 4.0-webkit |
| Feature | Android | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
| Basic support | ? | No support[1] | ? | ? | ? |
[1] Gecko currently doesn't implement this feature. It is only available in Nightly and Dev Edition. See bug 1251161.