The transparent, frameless Quick Entry window was created with
hasShadow: true. macOS derives a transparent window's native shadow
from its alpha content, but the boot HTML paints an opaque background
before the renderer forces transparency, so the OS caches a full-frame
shadow that renders as a stray grey rounded outline behind the card
(#99172). The other transparent overlays (pet, HUD) already run with
hasShadow: false; other platforms keep the native shadow.
Also fit the card's own CSS box-shadow inside the 12px transparent
padding budget (0 18px 48px clipped to a hard edge at the fixed window
bounds; 2+8 = 10px stays inside and fades cleanly).
Mirrors #83704.
Co-authored-by: Guangtong li <64474753+Marcus112-CS@users.noreply.github.com>
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