New answers tagged overlay-scrollbars
Not sure if it will work because I don't have this issue but my firefox is synced with my windows system and that may be why. If you click on the button in the right top corner (where you would click to get to preferences) then click on Customize in there you should see themes .. maybe try selecting a different theme might set it right.
What you could do is to install and use a complete theme for Firefox that includes its own scrollbars etc. This won't look like the old default, but I bet you can find something similar or even nicer. In the Tools menu, select Add-ons, there go to the Get add-ons tab and scroll down the page. In the lower left corner is a link See all complete themes. This ...
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