Flatpak - more configuration options

[balgerion]

Im loving your app and im using it on all my devices and one of them is arch linux so i need to use flatpak version. I dont know if you have room to add some options there but i would love to have little more configuration available

1. Left bar - text size and width size and option to hide it

2. Configuration of default web browser - this button don't open browser

3. option bar to follow theme Dark/Light - now its only white