Tl;Dr:
In about:config, I changed these preferences:
- widget.non-native-theme.gtk.scrollbar.round-thumb: false - This makes the scrollbar not have rounded edges
- widget.non-native-theme.gtk.scrollbar.thumb-size: 1 - This makes the scrollbar ‘chonkier’ within the scrollbar region
- widget.non-native-theme.scrollbar.size.override: 20 - This increases the scrollbar region size. Larger number = wider scrollbar
- Make sure widget.gtk.overlay-scrollbars.enabled is set to false - This should have been set to false when you enabled “Always show scrollbars”
On Windows, Firefox follows the system setting (System Settings > Accessibility > Visual Effects > Always show scrollbars).
I use the scroll bar at home mostly because the scroll wheel on my mouse is finicky. If I don’t scroll just right it’ll scroll down a little before scrolling right back up or just not scroll down at all. So it’s more convenient for me to just use the scroll bar.