✓ 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 air but writing-mode+direction:rtl makes top of the physical slider the maximum, so bottom=air/top=water); displaced-water info values are squared (multiplied by fracImmersed twice, i.e. goldDisp*fracImm instead of just goldDisp*pct/100 done once), and the water-rise scale (÷30 arbitrary) is not grounded in Archimedes physics; no genuine frame-by-frame fall animation, just a position jump driven by the slider.
Slider direction is inverted (min=0 at top maps to air but writing-mode+direction:rtl makes top of the physical slider the maximum, so bottom=air/top=water); displaced-water info values are squared (multiplied by fracImmersed twice, i.e. goldDisp*fracImm instead of just goldDisp*pct/100 done once), and the water-rise scale (÷30 arbitrary) is not grounded in Archimedes physics; no genuine frame-by-frame fall animation, just a position jump driven by the slider.