Expose a css library for use in widgets

All widgets are just straight html/css/js, and I think they would heavily benefit from a standard css framework as a base between all of them.

This isn’t neccessarily for visual style, but more for layout and utilities.

I think sticking to something very simple and straight forward like https://bulma.io/ would be very nice to have, since it doesn’t have any JS dependencies, and is very lightweight in general.