style links to pop more when hovered

the links in the dropdowns of the main nav didn't change at all on
hover, which is terribly unaccessable. also added a button class for
links that lead to actions.
fix the styles for the nav dropdowns

I had hacked together aboslutely positioned <ul>s which had hard-coded
widths to match the top level nav links and it didn't quite line up
right in different browsers or when you changed the zoom level. UGH.

but it's better now.