hoist-the-flag-not-the-animation

Share the boolean that drives a fade, never the tween that runs it — each look derives its own curve, so one can go asymmetric (fast in, slow out) without changing how the other feels; covers why a symmetric linear fade over a bright backdrop makes container-backed controls read as the wrong colour, and why the shared animated value must stay published anyway. Use when buttons look lighter or darker than their…