✓ 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 at top means crowns in air is correct by default, but the vertical slider's visual top corresponds to min=0 which is "in air", so direction is actually correct — however, the water level height calculation is broken: leftWaterHeight starts at 0 and the formula produces near-zero values since containerWidth=196 makes the divisor huge, so water barely rises; mass/volume/density are static labels not live-updating tspan elements, and there is no smooth fall animation — crowns jump linearly with no easing or distinct entry moment.
Slider direction is inverted (value=0 at top means crowns in air is correct by default, but the vertical slider's visual top corresponds to min=0 which is "in air", so direction is actually correct — however, the water level height calculation is broken: leftWaterHeight starts at 0 and the formula produces near-zero values since containerWidth=196 makes the divisor huge, so water barely rises; mass/volume/density are static labels not live-updating tspan elements, and there is no smooth fall animation — crowns jump linearly with no easing or distinct entry moment.