✓ 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
Slider direction is inverted (min=0 top→air, max=100 bottom→water uses writing-mode:vertical-lr + direction:rtl which renders top as 100/water on most browsers), and the gilded crown uses silver density rather than a realistic gold-silver alloy, but otherwise physics, visuals, live values, splash, water rise, and Heureka overlay are all solidly implemented.
Slider direction is inverted (min=0 top→air, max=100 bottom→water uses writing-mode:vertical-lr + direction:rtl which renders top as 100/water on most browsers), and the gilded crown uses silver density rather than a realistic gold-silver alloy, but otherwise physics, visuals, live values, splash, water rise, and Heureka overlay are all solidly implemented.