✓ 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 (label "Luft" at top, slider value increases downward in bt-lr writing mode causing correct physical movement, but the water-rise math is broken — `leftWaterRise = (leftDisplacedVolume / 148) * 148` trivially reduces to `leftDisplacedVolume`, meaning 51.8 cm³ raises water 51.8 px regardless of container scale, not physically calibrated; mass/volume/density values are static, not live-updating.
Slider direction is inverted (label "Luft" at top, slider value increases downward in bt-lr writing mode causing correct physical movement, but the water-rise math is broken — `leftWaterRise = (leftDisplacedVolume / 148) * 148` trivially reduces to `leftDisplacedVolume`, meaning 51.8 cm³ raises water 51.8 px regardless of container scale, not physically calibrated; mass/volume/density values are static, not live-updating.