/* nav.css — the site navigation: one link tree, three interaction contracts. Loaded after site.css, which still owns .gu-header's shell (sticky bar, inner flex row, logo box) and .gu-btn. Everything below either extends that or, where noted, deliberately overrides it. THE THREE CONTRACTS desktop >= 1080px mega panels, full header width, opened by pointer intent and by keyboard focus, with one panel image per section (desktop only, cloned from an inert