Content isn't loaded from rawgit in Firefox

[ahstro]

Neither bundle.js nor bundle.css seem to load in Firefox. I get both files if I open the rawgit URLs directly in the browser, and the REPL works fine in Chromium, but for some reason, I don't even see the requests going away in Firefox DevTools' Network tab. Don't have time to investigate right now myself.

[MattMS]

Could possibly be fixed by implementing #162, so I'll look into it after decisions are made on #175.