Make prettier

• Styled the elm-ui buttons (in a very generic way)
• Put everything on top of the 3d canvas (no more scrolling)
• Made the background platform dark-grey
• set responsive viewport scaling in html, to avoid scrollbars
• only show "connect cube button" when we haven't received any cube events
• Fix default cube orientation

It's still kind of rough and inconsistent, but much better than before.

In due time, I want to remove all buttons except "Connect Cube". Cube-first UI has to be the way to go.