Static front end for Spark, served from GitHub Pages at https://t4meri.github.io.
It talks to the Spark API on a different origin, so the session is held as a bearer token in
localStorage rather than a cookie. Third-party cookies are blocked by Safari and by Chrome
whenever the user turns them off, which would otherwise break sign-in.
config.js holds the API origin. Everything else in this repository is the same front end the
API serves for itself.