Enhancement: Easier branding css customisation

[ekostjuk]

Have been trying to do css override customisation to match our colour scheme, as using own sub-domain implies same styling requirements as rest of website.

Currently I have to inspect each element and see whether I can style it by id, need to go by class or outright override tailwindcss color preset or remove style field with additional js hack. Have to do it in cycles, producing a hacky and probably incomplete set of overrides that Im not sure will persist through future oneuptime updates.

There are probably a few ways to solve it. Starting from better docs/examples for css customisation. (list of classes/ids that you need to override colors on to cover "most" of it) Maybe exposing element colours via simplified tree in UI (like IDEs sometimes do). Probably after further standartisation. Maybe this could be standartised enough to capture several themes and allow for a custom one inheriting on closest match available.