Revisit and assess PR #1314

[jamesmisson]

#1314 makes some changes to CSS variables, but has been abandoned due to outstanding conflicts. Reappraise this and try to resolve conflicts if it looks like a good foundation for future plans for theming and dark/light mode.

[demiankatz]

I'm sure @crhallberg would be open to discussing this at some point (though he's quite busy right now with a local project). If you want me to set something up, just let me know!

[crhallberg]

I’m happy to try and resolve this. I’ve been away from the codebase for a while though, it may be worth starting over.