Cathode

A CRT / VHS tube background: a synthetic phosphor signal rolls under dense scanlines while a slow vertical tracking bar sweeps down and shears the picture, the whole frame barrel-distorted into a bulging glass tube with a dark bezel, radial chromatic aberration, phosphor bloom, aperture-grille shimmer, and animated snow — all graded through a single phosphor tint. Original OGL fragment shader, DPR-clamped, offscreen-paused, reduced-motion-safe.