✓ 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 maps crowns to top/air and bottom=water, but HTML range min=0 is visually at the top in a vertical slider, making 0→top correct in logic yet the slider thumb starts at bottom, and appearance:slider-vertical flips the axis — net effect is top of slider = submerged, bottom = air); no fall animation (crowns jump linearly, no free-fall easing); mass is static, not live; splash fires continuously while dragging rather than only at water-entry moment.
Slider direction is inverted (value=0 maps crowns to top/air and bottom=water, but HTML range min=0 is visually at the top in a vertical slider, making 0→top correct in logic yet the slider thumb starts at bottom, and appearance:slider-vertical flips the axis — net effect is top of slider = submerged, bottom = air); no fall animation (crowns jump linearly, no free-fall easing); mass is static, not live; splash fires continuously while dragging rather than only at water-entry moment.