- Fixes the height of the graph in FF
For some reason `height: calc(100% - 66px)` does something totally
different than `height: 100%`, but with `100vh` the behaviour is the
same either way. This seems like a FF CSS bug maybe…
- Use floating + margins instead of absolute positions for top bar
controls
Default button and input sizes are different across browsers and OSes,
by using floats + margins the positioning adapts to sizes instead of
having things drawn on top of each other.
