/* Site chrome — shared by index.html and 404.html.
*
* These two pages used to carry independent copies of the header and footer, and
* nothing detected when the copies disagreed. They drifted badly: the 404 had no
* nav, a non-sticky header, a differently-coloured and differently-sized footer,
* no `img { max-width }`, and a :root that was silently missing --brown-light.
* All of it shipped through a green bin/verify.
*
* So the chrome lives here, in one file, and cannot drift. What could not move —
* page-specific body layout, buttons, heading scales — stays inline on each page,
* and scripts/check_chrome_parity.py guards the header/footer MARKUP that is still
* necessarily duplicated. That gate also forbids these selectors from reappearing
* in a page's inline