On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 4 on 2010-01-25
In Chrome Android version 18 on 2012-06-27
In Edge version 12 on 2015-07-29
In Firefox version 4 on 2011-03-22 Note: Before Firefox 50, border styles of rounded corners were always rendered as if border-style was solid. This has been fixed in Firefox 50.
In Firefox for Android version 4 on 2011-03-29 Note: Before Firefox for Android 50, border styles of rounded corners were always rendered as if border-style was solid. This has been fixed in Firefox for Android 50.
In Internet Explorer version 9 on 2011-03-14
In Quest Browser version 5.0 on undefined
In Opera version 10.5 on 2010-03-02
In Opera Android version 11 on 2011-03-22
In Safari version 5 on 2010-06-07
In Safari on iOS version 4.2 on 2010-11-22
In Samsung Internet version 1.0 on 2013-04-27
In WebView Android version 4.4 on 2013-12-09
In WebView on iOS version 4.2 on 2010-11-22