Moves terminology box to component file

Moves terminology box to a component file. Adds general link styles to
links in the box.
Creates site-wide link mixin

Several areas of the app share the same link behavior of highlighting a
link when the cursor rolls over the main container containing a link.
This commit moves those styles to a mixin that can be shared among many
disparate parts of the app.
Adds bottom border to no results container

The no results container needed a light grey bottom border to be
consistent with the appearance of the page when the terminology box is
showing and no map is showing.