If you haven't noticed, the New Yorker also redesigned their top navigation. It's a brilliant design from https://twitter.com/mimicdecipher and implemented by https://twitter.com/erik_erikson
Had to go into reader mode to pull Firefox down from 50% CPU.
Safari on iPhone is one of the few implementations that actually works well, playing round with it a bit now it looks like it has quite a few heuristics to determine when to expand again. I guess most people don't care enough to actually spend the time adding more than just "show on drag down".