Deterministic checks on the global a11y layer (base/a11y.css): every interactive `.cs-*` control gets a real ≥44px hit target under a simulated coarse pointer (but each control's own documented floor (44px default; icon affordances/segmented/native-range are deliberately tiered lower per the CSS's own comments) reparsed via a brace-depth walk of base/a11y.css + button-size rules in base/components.css. Focus-visible is proven via static source scan, not live DOM focus (confirmed unreliable in this offscreen-iframe context — same class of issue documented in theme-overflow.html/contrast-guard.html): the universal rule in reset.css is real, and no base file silently strips outline without a replacement box-shadow. prefers-reduced-motion / prefers-contrast: more blocks are present and touch the expected selectors; every control keeps a real accessible name. Companion to a11y-gate.html (keyboard/ARIA interaction). Verdict on window.__a11ycss.