Backdrop display:block isn't media-scoped in fp_portal_sidebar.scss
(intentional — JS owns the drawer lifecycle). Without a resize
listener, opening the drawer at <=768px and resizing the browser
to >768px leaves the semi-opaque backdrop visible on desktop while
the sidebar visually snaps back to its sticky rail. Resize handler
calls toggleOpen(false) when crossing the breakpoint with .o_fp_open
still set.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>