The Hub "theme" menu is straight-forward and works well.
The general theme and styling in Hub is pretty good.
Has the Hub team ruled out allowing Hub site creators to use custom CSS classes?
What I imagine would work is that in the theme menu there would be a section at the bottom where a button would add new classes to a list of custom class definitions. There would be standard form fields to edit. The value, instead of being a strict color, would be any valid CSS enclosed in brackets.
