solidjs-motion

Layout (toggle)

Single motion.div whose width/height swaps via signal — `layout` FLIPs from the old rect to the new one via ResizeObserver(self).

Click the switch. The track's justify-content flips between flex-start and flex-end; <motion.div layout> on the handle catches the position delta and FLIPs the translate. No keyframes, no animation target — the parent's layout change is the only source.