Replace outdated UI library, cleanup UI

[anne-pc]

Rebass is long time without maintenance.
The way it's currently used within this project is far from ideal.
UI should be rewritten using a different library (or none) from ground up.

[anne-pc]

@axelboc I think I need some expert guidance. Given the simplicity of the "project" I probably should switch to just sass. However, if I really wanted to put that vanilla-extract in - I need a bit of extra tooling: I've looked at using craco but also into swapping CRA altogether with something different. With vite I ran into some complexity with jest, using vitest seems like the go to option in that case but one might use parcel etc. as well. Could you recommend a course of action, please?

[axelboc]

Hehe, I mean if you want to keep it simple, I'd recommend CRA + CSS modules. I like the simplicity of CSS modules. I think it overweighs the downside of having to write the styles in separate files or not being able to nest selectors.