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 ::-ms-fill CSS pseudo-element is a Microsoft extension that represents a progress bar displayed by <progress>. This pseudo-element is available only in Internet Explorer 10, Internet Explorer 11, and Microsoft Edge.

All allowable properties except animation-name apply to a determinate progress bar. Only animation-name applies to an indeterminate one. (A progress bar is determinate if it has a value attribute set; otherwise it is indeterminate. An indeterminate progress bar can be selected with the :indeterminate pseudo-class.)

By default, Internet Explorer and Edge display a moving dots animation for an indeterminate progress bar. By setting animation-name on ::-ms-fill, you can change the animation, as shown in this table:

Value Description
none Turns off the animation so that no dots are displayed.
-ms-bar Shows animated dots that flow in a bar pattern.
-ms-ring Shows animated dots that flow in a ring pattern.

Allowable Properties

Only the following CSS properties can be used in a rule with ::-ms-fill in its selector. Other properties are ignored.





<progress value="10" max="50"></progress>


progress::-ms-fill {
  background-color: orange;


A progress bar using this style might look something like this:

A progress bar with its progress indicator colored orange.

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support No Yes No 10 No No
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support No No Yes No No No ?


Not part of any specification.

See also

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