Darius Cepulis found two Safari feature flags in the iPhone Duo simulator: the Device Posture API, which reports whether the screen is continuous or folded, and the Viewport Segments API, which exposes both halves via media queries and env() variables. He used them to build a Netflix-style player with video on top and controls below. On a Pixel Fold emulator, fullscreen fills only the top half.
What the iPhone Duo means for web development (and Video.js)
