responsive design mastehead nav

[minty]

I think you've got some whizzy responsive design that's collapasing your top nav bar into a "popup" button when the browser width gets too narrow.

However, I think you might have the min-width value a little too high, as having a browser 900px wide, and the nav bar disappears seems a bit odd.

ps. you also have the "mobile" popup nav button in your top nav disapearing behind your "fork me on github" icon, which means when you try to click the nav bar button, you go to github. Dupe of #4