HelloSign: Everything IT requires and Developers love
Have you ever written this?
font-family: Helvetica, Arial, Sans-Serif;
You're all like: "Helvetica is the most awesome so I want that first, then Arial for PC's since hey it's pretty close, then fall back to whatever McSansSerif for crazyputers with like zero normal fonts installed."
Turns out this is way better:
Macs will get awesome Helvetica by default. On PC's, even if they have Helvetica it can look worse than Arial for whatever reason, so this way they get Arial by default. And you're still covered by the generic keyword. Shorter, easier, yay.