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
Canonical orderorder of appearance in the formal grammar of the values



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 AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic support
Chrome Full support 1Edge Full support 18Firefox No support NoIE No support NoOpera No support NoSafari Full support 4WebView Android ? Chrome Android ? Edge Mobile ? Firefox Android No support NoOpera Android No support NoSafari iOS ? Samsung Internet Android ?


Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
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

Document Tags and Contributors

Contributors to this page: fscholz, teoli, mfluehr, wbamberg, Sebastianz
Last updated by: fscholz,