A slide that arrives through a shape

Build one interactive web page: Three slides from an invented cycle workshop. The next slide, headline and all, is revealed through a rounded square standing on its corner, which turns upright and grows past the frame in 0.8 seconds. The old slide stays outside it, so for a moment the word is split across the seam. It is built from two nested boxes and nothing else: the outer one rotates and grows, the slide inside it turns the opposite way so it never tilts.

Set it on an invented business called Sampleton, with its own drawn or generated pictures and no one else's files. It suits: A short run of big statements or products, one headline each, on a brand whose identity has a shape in it. Anywhere a change of slide should feel like one object arriving. Do not let it fail the way this kind of piece usually does: A wipe that is slow, advances while someone is reading, or traps keyboard focus. Here it takes 0.8 seconds, the autoplay pauses under the pointer and on focus, the arrow keys and every button work, the readout reports the measured time, and reduced motion swaps slides at once.

It must work with the keyboard, on a phone, with reduced motion respected and no text under 12px. Tell me which libraries you chose and why.