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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-y CSS property sets the initial vertical position of a mask image.

/* Keyword values */
-webkit-mask-position-y: top;
-webkit-mask-position-y: center;
-webkit-mask-position-y: bottom;

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

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

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

/* Global values */
-webkit-mask-position-y: inherit;
-webkit-mask-position-y: initial;
-webkit-mask-position-y: 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 top side of the image relative to the box's top padding edge. Percentages are calculated against the vertical dimension of the box padding area. A value of 0% means the top edge of the image is aligned with the box's top padding edge and a value of 100% means the bottom edge of the image is aligned with the box's bottom padding edge.
Equivalent to 0%.
Equivalent to 100%.
Equivalent to 50%.

Formal syntax

[ <length-percentage> | top | center | bottom ]#

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


.exampleOne {
  -webkit-mask-image: url(mask.png);
  -webkit-mask-position-y: bottom;

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


Not part of any specification.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 ? No No No4
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support ? ? ? No No ? ?

See also

-webkit-mask-position, -webkit-mask-position-x, -webkit-mask-origin, -webkit-mask-attachment

Document Tags and Contributors

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