Confirmed on prod: rendering the iframe at 1920x1080 logical and CSS transform:
scale()-ing it down does NOT lift YouTube's quality cap — the embed stays ~360p in
the windowed player and manual HD still snaps back; only true fullscreen unlocks
1080p (which then persists for the session). YouTube caps by the on-screen size, not
the iframe's window.innerWidth, so the transform only shrank YouTube's native
controls for no benefit. Restore the plain 100%/100% mount.
Kept: scroll-anywhere volume (works), the native-menu-yield fix, max-w-6xl, and the
harmless vq=hd1080 hint.
peter
e678a267ae