First of – great work not only on Zen but also on Surfer. It's fascinating how suddenly Firefox has some kind of renaissance with indie browsers. Keep it coming.

Is your feature request related to a problem? Please describe.
Currently whenever you close the browser and restart, the sidebar's width is reset to the minimum width. While I find the collapsed sidebar nice and minimal I kinda miss a bit more info about a tab and prefer the "Arc" look.

However since the sidebar width resets everytime, I have to always reapply the size of the sidebar. Would be nice if this could somehow be stored.

Describe the solution you'd like
Store the sidebar width on change so it can be restored to that after collapse or an app restart.

Describe alternatives you've considered
No alternatives

Additional context
No additional context