A few paragraphs in to the article I was wondering what font the article was written in. I figured it might be Roboto and sure enough, a quick trip to Web Inspector shows it is.

I'm not a fan of Roboto personally as each character feels too narrow, squashed, and makes for tiring reading. I frequently check what fonts are in use when it's something unusual. The most beautiful by far that keeps cropping up is Proxima Nova.