This allows for the `HeightFixed` which is the same behaviour as V3,
`HeightBounded Int` which allows for a certain number of lines of text but no
more, and `HeightUnbounded` which will allow the button to grow in height
without bound.
The inclusion of reset.css file nuked the default browser styles for
headers. This change sees us using custom styled headers instead to
bring structure back to the styleguide pages.
