On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 50 on 2016-04-13
In Chrome Android version 50 on 2016-04-13
In Edge version 12 on 2015-07-29
In Firefox version 52 on 2017-03-07 Note: Before Firefox 3, the default value for the normal keyword was 0 and not 1em.
In Firefox for Android version 52 on 2017-03-07
In Internet Explorer version 10 on 2012-10-26
In Quest Browser version 5.0 on undefined
In Opera version 37 on 2016-05-04
In Opera Android version 37 on 2016-06-16
In Safari version 10 on 2016-09-20
In Safari on iOS version 10 on 2016-09-13
In Samsung Internet version 5.0 on 2016-12-15
In WebView Android version 50 on 2016-04-13
In WebView on iOS version 10 on 2016-09-13