On a page that centres its content at a max width, if the window is wide enough for the rail to fit
in the content's LEFT margin without overlapping it, pinning the rail now leaves it OVERLAY — the
content doesn't shift. It reverts to the old in-flow "push" only when there isn't room: a full-width
page (feed) or a window too narrow for the rail to clear the centred content.
PageShell computes --rail-pinned-w from the page's maxWidth vs the viewport (innerWidth >= maxWidth +
~576px → overlay 2.25rem, else in-flow 16.75rem) on a resize listener; the SidePanel slot reads it.
Verified at 1920px: pinning the playlists rail leaves the table at left 487 (moved 0); the rail sits
256px wide ending at 312 — 175px clear of the content. Feed (full width) still pins in-flow.
peter
53ca4e2849