User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 Steps to reproduce: I visit the site which I develop (I can provide the source and publicly available version if needed). I preform some actions on the site to bring it to the specific state. I right-click on the input and press "Inspect Element (Q)". The DOM inspector is opened. I hover the mouse cursor over the input element in DOM inspector. Actual results: Scrollbars are blinking fast, what results in page content shaking. You can see the instability of the page on the provided screenshot. Also I've recorded it on video: https://youtu.be/6Utjf9McNFw Expected results: Expected the page to be stable.