Refactor top bar

@keorn does Gitlab send you notifications when I mention you in my commit messages? Hope those don't get resend when I rebase.

Regarding the refactoring: Having less if-clauses reduces complexity. It's perfectly fine to have a slightly more verbose template. It also adds more control and easier customization (e.g. a different behaviour on the link to /standard).

As written in the commit message: A sidebar on all devices would be the easiest and best solution in my opinion.

Forget about "highlight the current route" that was already there befeore.