Start styling the Chord Drill Sergeant for mobile devices because that is that
device on which I will primarily use CDS.
I'm also deleting the debugger related code. I would like to support a debugger,
but I'm not currently using this one, so I am going to remove it to keep things
slender.
- Introduce TailwindCSS, which also introduced elm-live, index.html, index.css
- Add mobile-first styling for the preferences modal
- Remove unused code
