The combi-input popover flashed in the top-left corner for a frame, then
jumped into place. Two causes, both confirmed with a per-frame capture in
the browser:
1. The panel painted before floating-ui computed a position — gated its
visibility on `isPositioned` (hidden until positioned), same as
PopoverSurface.
2. The bigger one: the `popIn` entrance animation animates `transform`
(scale/translateY), and it sat on the SAME element floating-ui positions
via `transform` — so during the 0.16s animation the keyframes OVERRODE
the translate(x,y) and the panel rendered at the origin. Moved the glass
styling + popIn onto an inner child, leaving the positioned element's
transform untouched.
Frame capture after the fix: frame 0 hidden, first visible frame already at
translate(82,474) — never visible at the origin. Also gave the size
middleware a min width for a narrow rail.
peter
caced8664c