✓ 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 (hint labels say top=air/bottom=water but the vertical range input with `direction:rtl` maps slider-bottom to value=0/air and slider-top to value=100/water); everything else — ASCII dual-tank scene, correct physics (gold 19.3, fake 8.9 g/cm³, same 300 g mass), live readouts, splash, rising water arrows, and Heureka overlay — is solidly implemented.
Slider direction is inverted (hint labels say top=air/bottom=water but the vertical range input with `direction:rtl` maps slider-bottom to value=0/air and slider-top to value=100/water); everything else — ASCII dual-tank scene, correct physics (gold 19.3, fake 8.9 g/cm³, same 300 g mass), live readouts, splash, rising water arrows, and Heureka overlay — is solidly implemented.