✓ 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
Buoyancy force display is doubly calculated and wrong (millinewton rescaling errors; ~0.005 N shown for 1kg gold crown instead of ~0.51 N), and water-rise visual scale is an arbitrary 4× amplification that breaks physical fidelity, though all other features including splash, heureka overlay, live values, and dual-crown comparison are well-implemented.
Buoyancy force display is doubly calculated and wrong (millinewton rescaling errors; ~0.005 N shown for 1kg gold crown instead of ~0.51 N), and water-rise visual scale is an arbitrary 4× amplification that breaks physical fidelity, though all other features including splash, heureka overlay, live values, and dual-crown comparison are well-implemented.