3.1Beyond Screenshot Comparison

Traditional responsive testing took screenshots at different widths and compared them visually. This approach fails because it cannot distinguish between "the layout adapted correctly to a smaller width" and "the layout broke at a smaller width." Both look different from the desktop screenshot.

AI agents and modern testing tools can reason about functional correctness rather than pixel-perfect matching. The question is not "does it look the same?" but "does it work correctly at every width?"