I lost my arrows on my scrollbar again after an update early last month. I tried adding lines to the gtk.css config files with no success unlike I've been successful doing in the past. It appears they are gone forever unless I can find another way to get them back. I noticed that the scrollbar arrows are gone on only Firefox and Thunderbird. As mentioned, this has happened in the past after some updates but in the past I was able to edit the gtk.css files in both gtk-2.0 and gtk-3.0 to get them back. Is there anything else I can try. I'm using the latest version of Ubuntu (Pop OS to be specific) and the arrows to the scrollbars disappeared around April 2nd for both Firefox and Thunderbird. I didn't notice any other applications where the arrows to the scrollbars disappeared. Is there something else I can try and a way to prevent this from happening in the future. This seems to be a common problem that happens every time there is an update.