Add a shadow to the navbar.

It looks pretty groovy now.
Add a hover-box-shadow class to some of the navbar's elements.

This helps to obviate that something is hovered over.
Make the border-bottom on hovered things a little smaller.
Add some commented browser-specific box-shadow rules just in case.
Merge pull request #67 from kotct/navbar-accents

Adds some pretty effects to the navbar.