gpui's img element writes the image's aspect ratio into its own layout style, which overrides size_full in taffy: the element lays out at full width times aspect height, overflows its box, and the clip eats the bottom of every frame narrower than the box - object-fit never runs against the real box, so #:fit 'contain silently rendered as a top- anchored crop. Paint the frame directly in a canvas with ObjectFit math against the true bounds instead, and pin the decode path with a test that runs a real quoted symbol through the Steel engine. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>