/* ============================================================================
   MENU BACKGROUND PLATE — everything here is scoped to #menu-bg.
   #menu-bg is the first child of .menu-scene and sits *behind* the parallax,
   fog, grain and vignette layers that own the rest of that stack. Nothing in
   this file may style anything outside #menu-bg.

   Layer order inside #menu-bg (bottom to top):
     1. the poster still  — always present, so the panel is never a black hole
     2. the looping video — fades in only once it is actually playing
     3. the scrim         — keeps the title and menu list legible over it
   ========================================================================== */

#menu-bg {
  position: absolute;
  inset: 0;
  overflow: hidden;
  z-index: 0;
  pointer-events: none;
  /* the void colour of the front-end palette: whatever fails, this remains */
  background-color: #04060b;
  contain: layout paint style;
}

#menu-bg .menu-bg-still,
#menu-bg .menu-bg-video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  border: 0;
}

/* The poster is the video's own first frame, so the hand-off is invisible. */
#menu-bg .menu-bg-still {
  opacity: 0.92;
  filter: saturate(0.94);
}

/* Hidden until 'playing' fires. If the video 404s, is blocked by autoplay
   policy, or cannot be decoded, this simply never happens and the still
   stays on screen. */
#menu-bg .menu-bg-video {
  opacity: 0;
  transition: opacity 1100ms cubic-bezier(0.4, 0, 0.2, 1);
  will-change: opacity;
}
#menu-bg.is-live .menu-bg-video { opacity: 0.92; }

/* Sits over the footage: pushes the left third down so the title block and the
   numbered menu list keep their contrast, cools the whole plate toward the
   in-game steel-blue, and lets the floor fall away at the bottom. */
#menu-bg .menu-bg-scrim {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(
      90deg,
      rgba(4, 6, 11, 0.88) 0%,
      rgba(4, 6, 11, 0.72) 26%,
      rgba(4, 6, 11, 0.34) 54%,
      rgba(4, 6, 11, 0.16) 74%,
      rgba(4, 6, 11, 0.42) 100%
    ),
    linear-gradient(
      180deg,
      rgba(4, 6, 11, 0.62) 0%,
      rgba(4, 6, 11, 0.14) 22%,
      rgba(4, 6, 11, 0.2) 64%,
      rgba(6, 9, 15, 0.86) 100%
    ),
    radial-gradient(ellipse at 62% 46%, rgba(28, 46, 74, 0.16), transparent 62%);
}

/* Reduced motion: the still only. `display: none` also stops the browser from
   ever starting the download, so the clip costs nothing for these users. */
@media (prefers-reduced-motion: reduce) {
  #menu-bg .menu-bg-video { display: none; }
  #menu-bg .menu-bg-still { opacity: 1; }
}

/* Narrow viewports crop hard into the centre of the hall, which is the part
   that reads: the teleporter ring and the light shafts. */
@media (max-width: 760px) {
  #menu-bg .menu-bg-scrim {
    background:
      linear-gradient(180deg, rgba(4, 6, 11, 0.72) 0%, rgba(4, 6, 11, 0.3) 30%, rgba(4, 6, 11, 0.42) 66%, rgba(6, 9, 15, 0.9) 100%),
      radial-gradient(ellipse at 50% 44%, rgba(28, 46, 74, 0.14), transparent 66%);
  }
}