CSS Anchor Positioning Enables Smooth Grid Reflow Animations Without JavaScript

A technique using CSS anchor positioning allows auto-fill grid cells to animate smoothly during reflow, something previously impossible because grid cells lack interpolatable positions. Each cell gets a wrapper element assigned as a named anchor, while the visible content inside is absolutely positioned and stretches to match it using inset: anchor(inside). When the grid recomputes track layout, the browser interpolates the inset values over a plain CSS transition, making cells appear to glide rather than snap to their new positions. The approach requires no JavaScript, no ResizeObserver, and no View Transitions, and unlike View Transitions it remains interruptible mid-animation. Firefox currently does not support the transition, so a @supports feature-detect is recommended to gracefully fall back to the standard instant reflow behavior.