Animated Drop-In 404 Error Block for React

Each tile has a starting: style, a CSS rule for the first frame after it's inserted: it begins above the row and transparent, and a transition on its translate and opacity carries it to rest with cubic-bezier(0.34, 1.56, 0.64, 1), a curve that overshoots its target before settling. The three tiles wait 0, 250 and 500 ms (delay-0, delay-[250ms], delay-[500ms] in TILES), which is why the 0 lands last. The row clips the overshoot at the floor, so the tiles seem to press into it. Nothing loops and no script runs a frame.

It adds one to a counter, and the row of tiles is keyed by that counter, so React mounts a fresh row and the entrance runs from the start. A polite status line says "The numerals dropped again", with the round number so repeats are heard. It changes nothing else: the link and the words stay put, and the page keeps its height.

The transition is switched off, so the tiles are simply there when the page loads and again after Drop them again, which still works and still announces itself. The only other motion is the words fading up once, and that's off too.

The tiles are decoration, hidden from assistive technology: the heading says "Page not found" and the sentence says "Error 404" in words. Pressing a tile nudges it down 2 px with CSS, but tiles aren't controls and aren't in the tab order. The two real controls, the link and the replay button, have visible focus and come after the heading in reading order.

The link goes to #: point it at your home route. The 404 status is your server's job, so render the page from your framework's not-found route. Drop them again is purely cosmetic and needs no wiring; delete it, and the counter with it, if you want a one-shot entrance.

Edit TILES: each tile's delay is a literal class so Tailwind keeps it. For a slower drop, raise duration-700 on TILE; for a bigger bounce, raise the curve's second number a little. The tile sizes step up at the sm breakpoint with the numerals.