- Scope section trigger rules to div[data-state]:not([class]) so they
don't bleed onto other Radix collapsibles inside #nd-sidebar.
Fumadocs 15 section wrapper divs are bare (no class, no id); content
panels and popovers always carry a class attribute.
- Add focus-visible rings for section buttons and page links
(a11y gap from code review).
- Add !important to margin-top for consistency with the
surrounding padding overrides.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Activates fumadocs' built-in collapse on every section. Only the
section containing the current page expands; others stay collapsed
until the user clicks them. Foundation for the typographic sidebar
pass in the next commit.