✓ 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 (top label says "Luft/Air" but slider min=0 maps to air and dragging DOWN increases value toward water, which is correct semantically but the vertical CSS uses writing-mode+rtl making the physical top of the slider the high value — the visual top says "Luft" yet the rendered thumb starts at the bottom in most browsers, causing direction confusion); no genuine fall animation (crown teleports via RAF loop with no easing/gravity), but physics values, dual-crown data panel, water rise, splash particles, and Heureka are all solidly implemented.
Slider direction is inverted (top label says "Luft/Air" but slider min=0 maps to air and dragging DOWN increases value toward water, which is correct semantically but the vertical CSS uses writing-mode+rtl making the physical top of the slider the high value — the visual top says "Luft" yet the rendered thumb starts at the bottom in most browsers, causing direction confusion); no genuine fall animation (crown teleports via RAF loop with no easing/gravity), but physics values, dual-crown data panel, water rise, splash particles, and Heureka are all solidly implemented.