@jimunderscorep Must've screwed up my setup somehow. It works exactly as it should on a fresh Ubuntu.

@jimunderscorep Here's an example. Gnome tweaks changes everything UI wise, except for Opera, tabs and bookmark font size remains the same

I installed lxappearance but don't seem to have a setting for specifiying fonts and sizes

Anyone know how I can change the font-size of the UI? Gnome tweaks doesn't seem to affect Opera elements like tabs, address bar, etc, and the interface settings in Opera seem to be gone in v49