WIP: Much UI awesomeness

Fixes #89, #88, #85, #75, #73, #43, #41, #34.

@pdehaan r?
Not sure if these colors and `rgba()` should be moved into variables since they seem to be used in 1+ places.
Also need to see if we can do something like `rgba(#000, 0.2);` instead of the longer form. It seem to work in LibSass 2.0 (according to http://sassmeister.com/, but I'm not sure what version of libsass we're using via Grunt).