In dark mode the faint accent pools left the docked frosted chrome (nav/header) looking
flat — no content behind it to refract, unlike dialogs over the feed. Boost the dark-mode
ambient pools and make .glass a bit more translucent there so the chrome reads as glass
near the accent pools. Light mode unchanged. The full app-wide dark effect still needs
Phase 2 (ambient content/mosaic), deferred.