This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The -webkit-mask-position-x CSS property sets the initial horizontal position of a mask image.

/* Keyword values */
-webkit-mask-position-x: left;
-webkit-mask-position-x: center;
-webkit-mask-position-x: right;

/* <percentage> values */
-webkit-mask-position-x: 100%;
-webkit-mask-position-x: -50%;

/* <length> values */
-webkit-mask-position-x: 50px;
-webkit-mask-position-x: -1cm;

/* Multiple values values */
-webkit-mask-position-x: 50px, 25%, -3em;

/* Global values */
-webkit-mask-position-x: inherit;
-webkit-mask-position-x: initial;
-webkit-mask-position-x: unset;
Initial value0%
Applies toall elements
Percentagesrefer to the size of the box itself
Computed valuefor <length> the absolute value, otherwise a percentage
Animation typediscrete



A length indicating the position of the left edge of the image relative to the box's left padding edge. Percentages are calculated against the horizontal dimension of the box padding area. That means, a value of 0% means the left edge of the image is aligned with the box's left padding edge and a value of 100% means the right edge of the image is aligned with the box's right padding edge.
Equivalent to 0%.
Equivalent to 50%.
Equivalent to 100%.

Formal syntax

[ <length-percentage> | left | center | right ]#

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


.exampleOne {
  -webkit-mask-image: url(mask.png);
  -webkit-mask-position-x: right;

.exampleTwo {
  -webkit-mask-image: url(mask.png);
  -webkit-mask-position-x: 25%;


Not part of any specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 1Edge Full support 18Firefox Full support 49IE No support NoOpera Full support 15Safari Full support 3.2WebView Android Full support 2Chrome Android Full support 18Firefox Android Full support 49Opera Android Full support 14Safari iOS Full support 3.2Samsung Internet Android Full support 1.0


Full support  
Full support
No support  
No support
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.

See also

-webkit-mask-position, -webkit-mask-position-y, -webkit-mask-origin, -webkit-mask-attachment