Plan step 36 browser-test run, reviewer checklist. Only a plain, opening/closing sanity check existed for a selected row's background; this proves the state layer mixes over the secondary-container fill rather than in place of it, on the showcase's design-review.mp4 row — the same guarantee list.css already has, from a real hover and focus in the browser rather than only the Feature-level CSS declarations. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9