This allows us to include _theme to get all the variables. The
idea is that we may, in the future, be able to use a few different
CSS files if we have complex (= large) features which are only
needed rarely.
- Create a colour palette
- Create a sizing schema for paddings and fonts
- Implement basic form controls
- Create a theme demo page
- Apply the theme to the existing pages.
Still TODO is the final font selection.
