Nav accessibility

- Added aria tags to nav and dropdowns
- Minor style updates
  - Moved nav link color to a variable
  - Right side of section headers have a negative margin to better fit under heading
yup that's a great example! This one goes through some more detail as well http://terrillthompson.com/blog/474
The point is that without keyboard navigation, adding aria roles will only confuse users as it implies they'll be able to do something with that menu, but in its current state they can't. In the future, I suggest adding keyboard functionality first, before ARIA markup. ARIA is meant to describe functionality, so it's better to have that functionality in place already.
Anything you're adding should also be tested in a few screen readers as well to make sure it's actually helpful and makes sense. This is something I can help you get going with if you're interested. Don't meant to discourage you from looking into a11y stuff, but especially with screen readers, a lot of factors have to come together otherwise it's just noise for users.