✓ 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
Near-complete implementation with correct physics (19300 vs 5000 kg/m³, same mass), live panel values, water rise, splash particles, ripples, bubbles, per-crown displacement bars, and a confetti Heureka overlay — minor flaw: splash trigger fires randomly every frame in the sv 48–55 range instead of once on entry, causing redundant particle storms.
Near-complete implementation with correct physics (19300 vs 5000 kg/m³, same mass), live panel values, water rise, splash particles, ripples, bubbles, per-crown displacement bars, and a confetti Heureka overlay — minor flaw: splash trigger fires randomly every frame in the sv 48–55 range instead of once on entry, causing redundant particle storms.