✓ 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/top=air is correct in principle, but writing-mode bt-lr with appearance:slider-vertical means the thumb sits at the bottom when value=0, making top=water/bottom=air visually); crown rendering is simplistic circles with orbiting dots rather than actual crown shapes, and the submerged-fraction calculation is geometry-naive.
Slider direction is inverted (min=0/top=air is correct in principle, but writing-mode bt-lr with appearance:slider-vertical means the thumb sits at the bottom when value=0, making top=water/bottom=air visually); crown rendering is simplistic circles with orbiting dots rather than actual crown shapes, and the submerged-fraction calculation is geometry-naive.