Reserve space before images finish loading
The practical problem
Product pages can shift repeatedly if newly decoded cover art pushes descriptive text and pricing controls downward.
Implementation protocol
Set intrinsic width and height and retain aspect-ratio-aware CSS. For art-directed picture sources, confirm the intended ratio in each alternate layout.
Worked scenario
A 400×240 cover sets a 5:3 slot; a portrait replacement should declare its true dimensions rather than borrow those of the desktop source.
What could go wrong
Using object-fit without a reserved slot does not itself stop layout shift.
Acceptance criteria
Test slow-network render and text scaling in a 390-pixel viewport.
Source material and evidence boundaries
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