✓ 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
All 21 required features are implemented; the custom SVG drag-slider works correctly (top=air, bottom=water), iterative water-rise calculation is physically sound, and the Heureka animation fires at full submersion — minor weakness is a custom SVG thumb (not a native range input) whose drag area can slip under rapid mouse movement.
10,364 output tokens · claude-opus-4-6 · end_turn
All 21 required features are implemented; the custom SVG drag-slider works correctly (top=air, bottom=water), iterative water-rise calculation is physically sound, and the Heureka animation fires at full submersion — minor weakness is a custom SVG thumb (not a native range input) whose drag area can slip under rapid mouse movement.