— Two crowns — Same mass, different density — Vertical slider — Slider works — Slider controls crowns — Slider direction correct — Full slider range — Fall animation ✓ Water displacement ✓ Rising water level — Splash effects — Physics correct — Live mass value — Live volume value — Live density value ✓ Live displaced water — Gilded displaces more — Heureka animation ✓ No external deps ✓ Light bg / dark text ✓ Self-contained HTML
Implements a generic Archimedes buoyancy demo with buttons and drag-and-drop cubes, but completely omits the required crown scenario, vertical slider, fall/splash animations, Heureka moment, and per-crown physics values (mass, volume, density).