More specific fonts and padded/rounded code blocks

Courier is hideous on Linux, so I added some fonts while keeping the fallback. The git commands are now padded and rounded so everything is a bit more readable and visually consistent.

In Chrome it looks like:
![bridge_card](https://f.cloud.github.com/assets/358882/247335/48b4a466-8ad4-11e2-9544-4489abdb2d29.png)

The deployed version of the page is busted in Firefox. Working on that in another PR (hopefully)