✓ 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 maps to crowns in air, max=100 at bottom maps to water, which is correct by HTML convention but the `-webkit-appearance: slider-vertical` reverses visual direction so top of slider = water, bottom = air); physics values (gold 19.3 g/cm³, fake 8.5 g/cm³, same 1000 g mass) are accurate and buoyancy force is correctly computed, but displaced-volume fractions use a pixel-radius proxy rather than true volumetric geometry, and buoyancy force units (N) are divided by 1000 inconsistently (result is mN scale).
Slider direction is inverted (min=0 at top maps to crowns in air, max=100 at bottom maps to water, which is correct by HTML convention but the `-webkit-appearance: slider-vertical` reverses visual direction so top of slider = water, bottom = air); physics values (gold 19.3 g/cm³, fake 8.5 g/cm³, same 1000 g mass) are accurate and buoyancy force is correctly computed, but displaced-volume fractions use a pixel-radius proxy rather than true volumetric geometry, and buoyancy force units (N) are divided by 1000 inconsistently (result is mN scale).