✓ 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 (slider min=0 at top maps to crowns in air, but HTML range vertical sliders have value=0 at bottom in most browsers, making top=100=water and bottom=0=air — net effect is inverted UX); no smooth fall animation (crowns teleport linearly with slider, no timed drop sequence); physics values are plausible and gilded crown correctly displaces more water.
Slider direction is inverted (slider min=0 at top maps to crowns in air, but HTML range vertical sliders have value=0 at bottom in most browsers, making top=100=water and bottom=0=air — net effect is inverted UX); no smooth fall animation (crowns teleport linearly with slider, no timed drop sequence); physics values are plausible and gilded crown correctly displaces more water.