The Showcase Page Spec: A11y-First by Design, Not Afterthought

DS-V3.2 detailed the accessibility-showcase.html toggle UX: real button elements with aria-pressed, yellow 3px dashed focus rings, ARIA live regions for state announcements, Tab-key spatial navigation cycling through toggles, Escape to return to menu, Space/Enter to toggle. GPT-5 added further a11y requirements: :focus-visible ring 3px solid currentColor with 2px offset, role=status with aria-live=polite, honors prefers-reduced-motion and prefers-contrast. This isn't a demo — it's a reference implementation of accessible web component design.