✓ 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
Exceptionally complete implementation hitting every required feature — physics values are correct (ρ_gold=19.3, ρ_fake=8.5, same 1000g mass), slider direction is correct (0=air, 100=water), water rise, splash/bubble particles, live panel values, comparison bars, and a polished confetti Heureka modal all present; minor weakness is that visual water-rise scaling (× 0.5 px/cm³) is arbitrary rather than geometrically derived from tank cross-section, so the displayed rise arrows are cosmetic rather than physically proportional.
Exceptionally complete implementation hitting every required feature — physics values are correct (ρ_gold=19.3, ρ_fake=8.5, same 1000g mass), slider direction is correct (0=air, 100=water), water rise, splash/bubble particles, live panel values, comparison bars, and a polished confetti Heureka modal all present; minor weakness is that visual water-rise scaling (× 0.5 px/cm³) is arbitrary rather than geometrically derived from tank cross-section, so the displayed rise arrows are cosmetic rather than physically proportional.