Fixes 917588 - restore pre-refactor behaviors

Restores plot onhover behavior, cosmetic space between product and
version in the version selector, and makes some CSS tweaks to restore
a solid color header and reduce wasted horizontal space.

If the "add plot" functionality is restored multiple plots should look
pretty alright.

This also fixes a bunch of little things that set of jshint, like missing semicolons or no-seriously-this-time-comparators when comparing to `null` or `0`.