M3 § Text Fields, Behaviour: compact may let a field span full width, but medium and expanded must bound it — "never let it span the full width of a large screen". Nothing in the package capped a field (plan step 24, audit docs/audits/m3-alignment/inputs.md § Missing). From `medium` a field now stops at 40rem — the site names no number, so the header says where this one comes from — which a `max-w-*` class beats and `full` takes off. The search bar already carries M3's own 720px. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9