User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:53.0) Gecko/20100101 Firefox/53.0 Build ID: 20170518000419 Steps to reproduce: https://jsfiddle.net/3def1vff/13/ Div with position absolute is incorrectly positioned when blur CSS is applied. See jsfiddle and click button to enable blur. Compare results to Chrome if needed. Actual results: The div oscilates between the top left of the containing div and the bottom right when you mousemove over it. Expected results: The div should remain in the bottom right.

I submitted this bug on my home machine. NoScript is interfering with the jsfiddle, so I can't verify it on this machine. I repro'd and created the Fiddle in Firefox 53 on Windows.