Style improvements v2

Bryan,

The main focus of this branch was to get individual articles looking better on desktop and phones, but I also did a bunch of other minor UI refactors on how article summaries are treated in the index view. Take a look at let me know if you like how it all looks.

Also, I found the design needing an off-white BG on the index view in order to make each summary feel distinct and easy to click, which meant needing some way to switch back to a pure white BG when on single article views. I'm sure there's a better way to accomplish this than how I wound up doing it.