A plain CSS grid of invisible cells reflows instantly; every swatch is anchored to its cell with
data-⚓️-fill and glides after it (data-⚓️-transition="glide",
data-⚓️-scope-name so all cells share one anchor name). Filters toggle hidden,
sorting and dragging only change each cell's CSS order. Drag a swatch (grip on touch) or
focus one and press Alt+←/→.