Big refactor of CSS to truly be mobile/content-first

Sorry this PR is so huge. It will probably be easiest to run the site with these changes and we can talk through them by looking at things in a browser.

### Todos

- [x] Fix labels on Grids unit bar chart
- [x] Fix Paginator docs because of `border-box`
- [x] Uncomment `-webkit-overflow-scrolling: touch;`