✓ 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 is top/air which maps correctly by CSS but the `writing-mode: vertical-lr; direction: rtl` combo makes the physical top of the slider correspond to max=100/water, breaking the expected top=air convention); physics, ASCII art rendering, live values, splash, water rise, and heureka overlay are all solidly implemented.
Slider direction is inverted (value=0 is top/air which maps correctly by CSS but the `writing-mode: vertical-lr; direction: rtl` combo makes the physical top of the slider correspond to max=100/water, breaking the expected top=air convention); physics, ASCII art rendering, live values, splash, water rise, and heureka overlay are all solidly implemented.