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 :-moz-window-inactive CSS pseudo-class is a Mozilla extension that matches any element while it's in an inactive window.

:-moz-window-inactive works in content HTML documents, too.

Note: Prior to the addition of this pseudo-class, giving different styles to background windows was achieved by setting an attribute (active="true") on the top-level XUL chrome window. This attribute is no longer used.


This example alters the appearance of a box's background depending on whether its window is active or not.


<div id="mybox">
  <p>This is a box!</p>


#mybox {
  background: linear-gradient(to bottom, yellow, cyan);
  width: 200px;
  height: 200px;

#mybox:-moz-window-inactive {
  background: cyan;


You can view this as a live sample here as well.


Not part of any specification. This is a proprietary pseudo-class specific to Gecko.

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support No support No support 4.0 (2)[1] No support No support No support
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support No support No support No support No support No support

[1] Implemented in bug 508482.

Document Tags and Contributors

Last updated by: teoli,