✓ 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 at top means crowns in air, but the -webkit-appearance:slider-vertical with direction:rtl maps drag-down to increasing value — visually ambiguous and non-standard; in practice the label says "drag down" but the CSS rtl+vertical combination means dragging down decreases value on most browsers, making the direction wrong); otherwise an exceptionally complete and polished implementation with correct physics, particle splashes, buoyancy arrows, displacement bar chart, and a well-animated Heureka overlay.
Slider direction is inverted (min=0 at top means crowns in air, but the -webkit-appearance:slider-vertical with direction:rtl maps drag-down to increasing value — visually ambiguous and non-standard; in practice the label says "drag down" but the CSS rtl+vertical combination means dragging down decreases value on most browsers, making the direction wrong); otherwise an exceptionally complete and polished implementation with correct physics, particle splashes, buoyancy arrows, displacement bar chart, and a well-animated Heureka overlay.