fix: Show footnotes on small screens

[TwoTau]

Fixes #24

The CSS changes are to make the footnote number a teensy bit bigger on smaller screens.

[TwoTau]

Not sure if we want to increase the touch target size of the footnote even more. This is what it looks like now on mobile:

[jheer]

Thanks @TwoTau. I just merged the monorepo branch which unfortunately conflicts with this PR. Do you mind updating in response?

• Components are now in packages/components
• CSS styles are in packages/compiler with a layout similar to before

[jheer]

Thanks!