The viewing

Build one interactive web page: A three-bedroom semi on Sampleton Estates, four rooms of ordinary photographs and a magnifier. Click through them and come back: in the hall she is a shape in a far doorway, then halfway down the carpet; in the lounge a figure in the mirror, then at the bay window; at the kitchen window, in the wardrobe gap. She only ever moves while you are looking at a different photograph, so you can never catch it. The magnifier is yours, and the dark corners are where she is: stare, or go in close, and her face is cut into the picture. After the twelfth photograph there is a thirteenth, of you at your desk, with her behind your chair. The page takes the magnifier out of your hand, carries it to her face, and she screams.

Set it on an invented business called Sampleton, with its own drawn or generated pictures and no one else's files. It suits: A Halloween event, a horror film or game launch, a haunted attraction: anywhere a visitor has come to be properly frightened by something that looks like an everyday page. The change-between-glances loop suits any piece that wants dread without ever showing a monster for long. Do not let it fail the way this kind of piece usually does: A scare that ambushes with no warning, flashes, or takes the page away. Here a content note comes first, there is never a flash, only the magnifier is taken (the page and your pointer stay yours), the whole thing can be watched hands-free, sound is off until you turn it on, and Look again returns to the hall. Reduced motion stops the shake and the grain.

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.