8ef50b183e
The panel's display:flex overrode the browser's default [hidden] styling,
so it rendered open from first paint and the close button was inert. Added
a global [hidden]{display:none!important} guard so the attribute always
wins. Browser-verified: loads minimized, opens, closes, toggles. Assets
v=20260904l.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>