✓ 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 (value=0 is "up/air" per code logic but HTML range with `direction:rtl` on a vertical slider means dragging down increases value, which is correct behavior, however the crown enters water only after ~60% of slider travel due to geometry mismatch, making the early slider range feel dead; no fall animation — crowns jump position rather than falling smoothly.
Slider direction is inverted (value=0 is "up/air" per code logic but HTML range with `direction:rtl` on a vertical slider means dragging down increases value, which is correct behavior, however the crown enters water only after ~60% of slider travel due to geometry mismatch, making the early slider range feel dead; no fall animation — crowns jump position rather than falling smoothly.