Fix: nav dropdowns rendered as raw text on three pages

• The bug. On Who can pull the plug, Accepted is not acceptable and How it works, both dropdown panels rendered open and unstyled — their items spilling across the header as run-together text ("How it worksAgents"). The other eight pages were fine.
• The cause. Those three stylesheets were written from a shared shell that predated the dropdown menu, so they carried the mobile rules for .navgroup / .navmenu but none of the desktop ones. With no position:absolute and no display:none, the panel simply laid out inline. Nothing failed — the markup was correct and the JavaScript worked; there were just no rules to hide it.
• The fix adds the canonical dropdown block to all three, so every page styles the shared header identically.
• The gate. Every page renders the same <rm-menu>, so the build now checks that every page stylesheet defines the rules that header needs — anchored to top-level selectors, because the same names appear indented inside the mobile media query and matching those would let a page pass with no desktop rules at all. Verified by deleting the rule and watching the build fail. A smoke group also asserts the panel is hidden, positioned out of flow, and opens on click, on every page.