The sign-in page was the last bare doorway into the dressed admin. The palette and control skin now live in one class-scoped stylesheet, lib/styles/letterhead.css, imported by both the admin layout and the login page instead of being duplicated per surface. The login page gets the airmail stripe, wordmark masthead, and the shared form skin, with the handle label in the mono system voice the landing lookup uses, plus aria-invalid/aria-describedby wiring on a failed submit. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>