Replace ~48 magic z-index values (z-10..z-[9999] + 2 inline zIndex) with named
tailwind zIndex tokens (base/menu/chrome/paneltab/panel/rail/overlay/popover/
tooltip/tuner). Values are UNCHANGED — a rename, not a renumber — so layering is
identical; the names give one source of truth for the stack.
The tab stays mounted under the open card on purpose, but the card's 17px corner
radius cuts away its own pixels and the tab's square docked corner sits right
under that arc — showing a hairline of tab glass. Fade the tab out while the
card is open; opacity-0 rather than invisible/hidden, so it stays hoverable and
focusable (that is the whole reason it stays mounted).
The shared SidePanel now follows the nav rail's model, so Filters, Plex and
Playlists all inherit it: unpinned it sits as a small tab docked flush against
the rail (replacing the full-height vertical strip) and expands into the card on
hover or keyboard focus without pushing content; pinned it stays expanded
in-flow. The collapse toggle became pin/unpin, and panels now default to
unpinned. The tab carries the active-filter count and an accent ring.
The tab stays mounted under the open card on purpose: swapping it out from under
the pointer drops the hover that opened the card, and unmounting it while
focused strands keyboard focus.
Measured: feed content starts at 123px instead of 336px when unpinned.
Replace the full-height filter rails with one shared floating glass SidePanel
used by Feed, Plex and Playlists. Each collapses to a slim tab beside the nav;
its sections are reorderable "islands" (drag / hide / per-group collapse) with a
per-panel saved layout; the body hides its scrollbar with a soft top/bottom edge
fade. The nav rail becomes a matching floating rounded card.
- New shared SidePanel / PanelGroup / PanelGroups + useScrollFade hook.
- Generalise the feed-only sidebarLayout into a per-panel panelLayout (feed keeps
its storage key; plex/playlists get their own; persisted per account).
- Lift the Playlists rail to App level (selected playlist is now App state) so it
floats and collapses like the filter rails; remove the old CollapsedFilterRail.
- The floating top header's fixed offset accounts for the panels' margins.
peter