We could do something with Javascript to only show the selected template. For
now this is something that works without Javascript.
This means we can put off getting the build and testing pipeline for Javascript
set up, which is a bigger and more unknown piece of work.
Main thing that was missing was including the main CSS file in the template.
There are a few hacky bits here, like moving the whole of toolkit inside the
stylesheets directory.
Would arguably be cleaner using something that isn’t Flask Assets, but that’s
something for later.
