✓ 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 maps to crowns-in-air at top, but the vertical range input renders with 0 at bottom on most browsers, so bottom=air/top=water), and the vertical slider uses a partially deprecated `appearance: slider-vertical` approach that may not render correctly cross-browser; all physics, live values, ASCII art scene, splash effects, and the animated Heureka overlay are impressively well-implemented.
Slider direction is inverted (min=0 maps to crowns-in-air at top, but the vertical range input renders with 0 at bottom on most browsers, so bottom=air/top=water), and the vertical slider uses a partially deprecated `appearance: slider-vertical` approach that may not render correctly cross-browser; all physics, live values, ASCII art scene, splash effects, and the animated Heureka overlay are impressively well-implemented.