✓ 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
Physics values are critically broken: density is computed as mass/submerged-volume-fraction rather than the fixed material density, so density changes as the slider moves instead of being a constant property of each crown, and a gold density of ~20 g/cm³ only shows when fully submerged; slider direction is inverted (value=0 means crown in air, value=100 means submerged, but HTML range sliders visually render 0 at top, so top=air is actually correct for mouse interaction yet the crown Y-position math is convoluted and there is no true fall animation — crowns teleport rather than fall).
Physics values are critically broken: density is computed as mass/submerged-volume-fraction rather than the fixed material density, so density changes as the slider moves instead of being a constant property of each crown, and a gold density of ~20 g/cm³ only shows when fully submerged; slider direction is inverted (value=0 means crown in air, value=100 means submerged, but HTML range sliders visually render 0 at top, so top=air is actually correct for mouse interaction yet the crown Y-position math is convoluted and there is no true fall animation — crowns teleport rather than fall).