Follow-ups on the 7-item batch:
- The slim nav slot was still w-20 while its card is w-14, leaving a ~24px dead
gap the filter tab/bar couldn't dock against. Slot is now w-14 (exactly the
card width), so the filter's flat-left tab sits flush on the rail's right edge
(measured gap 0), both collapsed and expanded.
- The Plex art backdrop was invisible: a position:fixed layer at z-index -1 is
painted BEHIND the body's opaque background here, so nothing showed. Paint the
art on the app root (#root) instead — it's exactly the viewport and a real
ancestor of the transparent nav/header/content, so the art fills the whole page
edge-to-edge and the glass chrome floats over it (verified in-browser).