The green button to add troubleshooting information couldn't find what I was looking for, and upon my return I need to rewrite my post. Drat! I asked this once before, for Firefox does not follow the system default color scheme. See the attachment. Now running 65.0.1, and according to Mozilla article on CSS Scrollbars, https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Scrollbars, this is supported since version 64. But this also looks more like something I put in my website to color your Firefox scrollbars, not affect my own Firefox systemwide. My scrollbar style is MY property, and I don't believe web authors have any business changing them to their liking, No website of mine will change my visitors' scrollbars. The question I have is, how and where can I make changes to reverse the color scheme of my Firefox to match the rest of my system? I searched "scrollbars" in about:config and found a bunch of entries applied by a deprecated extension that is no longer around: They start with "extensions.noiascrollbars-extension." I assume these could be removed, but they are causing no harm that I am aware of because the scrollbars are just as they were before the extension was used. Running Linux Mint 17.3 (due for a 19.1 DVD!). IBM System X3200 Server 64bit. Thank you.