✓ 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 is air, dragging toward bottom increases value toward water, but the label says "LUFT" at the bottom not top, and the crown moves up not down as value increases — logic is correct but UX labeling is confusing); mass, volume, and density values are static/hardcoded rather than live-updating, and there is no smooth fall animation — only instantaneous position jumps.
Slider direction is inverted (min=0 is air, dragging toward bottom increases value toward water, but the label says "LUFT" at the bottom not top, and the crown moves up not down as value increases — logic is correct but UX labeling is confusing); mass, volume, and density values are static/hardcoded rather than live-updating, and there is no smooth fall animation — only instantaneous position jumps.