Deep visual-regression review assist, not a numeric gate: this environment can't rasterize nested-iframe content (html-to-image limitation) and the baselines in _audit/baselines/ are downscaled 909×540 references — so drift is judged by eye. Pick a baseline, then compare side-by-side, or Overlay (difference) — where the live render matches the baseline the blend goes black; anything that lights up has moved. Adjust native width if the overlay is misregistered. The runner includes this page as an advisory row (baseline freshness: every declared baseline exists + its live source resolves — window.__visualdiff).
Add a baseline: open the template directly, capture it at its native width into a 16:9 frame, save as _audit/baselines/<slug>.png, then add <slug> here. Baselines are intentionally few (product · document · deck exemplars) — they anchor the archetypes, not every template. Regenerate after an intentional redesign so the baseline reflects the new truth.