/* ============================================================
 * style_backdrops.css — the backdrop layers, 4 CSS designs, swatches, panel (#3d)
 * Low-compute by construction: transform/opacity/filter animations only (compositor-friendly),
 * a couple of oversized gradient elements, no layout work per frame. Reduced-motion freezes all.
 * ============================================================ */

/* The two layers share the aurora's plane, behind everything. */
#backdrop-canvas, #backdrop-css {
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
}
#backdrop-canvas { width: 100%; height: 100%; display: none; }
#backdrop-css { display: none; overflow: hidden; }
#backdrop-css[class^="bd-"], #backdrop-css[class*=" bd-"] { display: block; }

/* While a non-aurora backdrop is active, the aurora canvas hides (its loop is also paused). */
html.backdrop-active #aurora-bg { display: none; }

/* Pause switch for the CSS designs (canvas designs stop their loop instead). */
#backdrop-css.bd-paused, #backdrop-css.bd-paused::before, #backdrop-css.bd-paused::after
  { animation-play-state: paused !important; }

/* ── NOVA — the ULTRA-BRIGHT one: breathing white-gold light ─────────────────── */
#backdrop-css.bd-nova { background: #fdfbf6; }
#backdrop-css.bd-nova::before, #backdrop-css.bd-nova::after {
  content: '';
  position: absolute;
  inset: -30%;
  background:
    radial-gradient(42% 38% at 30% 32%, rgba(255,214,140,0.85), transparent 70%),
    radial-gradient(46% 42% at 72% 64%, rgba(160,205,255,0.75), transparent 70%),
    radial-gradient(36% 34% at 56% 22%, rgba(255,170,190,0.55), transparent 70%);
  animation: bd-nova-drift 26s ease-in-out infinite alternate;
}
#backdrop-css.bd-nova::after {
  animation-duration: 34s;
  animation-direction: alternate-reverse;
  opacity: 0.7;
  transform: scale(1.15) rotate(24deg);
}
@keyframes bd-nova-drift {
  from { transform: translate(-4%, -3%) scale(1); }
  to   { transform: translate(4%, 3%) scale(1.12); }
}

/* ── SILK — drifting blurred colour blobs ────────────────────────────────────── */
#backdrop-css.bd-silk { background: #101422; }
#backdrop-css.bd-silk::before, #backdrop-css.bd-silk::after {
  content: '';
  position: absolute;
  width: 62vmax; height: 62vmax;
  border-radius: 50%;
  filter: blur(70px);
  opacity: 0.5;
}
#backdrop-css.bd-silk::before {
  left: -12vmax; top: -14vmax;
  background: radial-gradient(circle, #6a5cff, transparent 65%);
  animation: bd-silk-a 37s ease-in-out infinite alternate;
}
#backdrop-css.bd-silk::after {
  right: -14vmax; bottom: -16vmax;
  background: radial-gradient(circle, #0fb8a8, transparent 65%);
  animation: bd-silk-b 43s ease-in-out infinite alternate;
}
@keyframes bd-silk-a { to { transform: translate(22vw, 16vh) scale(1.25); } }
@keyframes bd-silk-b { to { transform: translate(-20vw, -14vh) scale(0.85); } }

/* ── GRID — scrolling neon horizon ───────────────────────────────────────────── */
#backdrop-css.bd-grid { background: linear-gradient(#03040a 55%, #0b1030); }
#backdrop-css.bd-grid::before {
  content: '';
  position: absolute;
  left: -25%; right: -25%; top: 52%; bottom: -12%;
  background:
    repeating-linear-gradient(90deg, rgba(90,140,255,0.5) 0 2px, transparent 2px 88px),
    repeating-linear-gradient(0deg,  rgba(90,140,255,0.5) 0 2px, transparent 2px 62px);
  transform: perspective(420px) rotateX(58deg);
  transform-origin: 50% 0;
  animation: bd-grid-run 5.5s linear infinite;
  mask-image: linear-gradient(rgba(0,0,0,0.9), transparent 92%);
  -webkit-mask-image: linear-gradient(rgba(0,0,0,0.9), transparent 92%);
}
#backdrop-css.bd-grid::after {
  content: '';
  position: absolute;
  left: 0; right: 0; top: 38%; height: 26%;
  background: radial-gradient(48% 100% at 50% 100%, rgba(120,80,255,0.5), transparent 75%);
}
@keyframes bd-grid-run { to { background-position: 0 62px, 0 62px; } }

/* ── PULSE — hue-rotating soft conic mesh ────────────────────────────────────── */
#backdrop-css.bd-pulse { background: #0a0a14; }
#backdrop-css.bd-pulse::before {
  content: '';
  position: absolute;
  inset: -22%;
  background:
    conic-gradient(from 40deg at 32% 38%, #3a1c7a, #103a7a, #0c6b62, #3a1c7a),
    radial-gradient(60% 60% at 70% 66%, rgba(255,255,255,0.06), transparent 70%);
  filter: blur(46px) saturate(1.3);
  animation: bd-pulse-hue 22s linear infinite;
}
@keyframes bd-pulse-hue {
  from { filter: blur(46px) saturate(1.3) hue-rotate(0deg);   transform: scale(1); }
  50%  {                                                       transform: scale(1.07); }
  to   { filter: blur(46px) saturate(1.3) hue-rotate(360deg); transform: scale(1); }
}

/* ── The picker panel ────────────────────────────────────────────────────────── */
.backdrop-body { display: flex; flex-direction: column; gap: 12px; max-width: 380px; }
.bd-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.bd-swatch {
  display: flex; flex-direction: column; align-items: center; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 4px; border-radius: 12px;
  color: inherit; font-size: 11px; font-weight: 600; min-height: 44px;
}
.bd-swatch-face {
  width: 100%; aspect-ratio: 4 / 3; border-radius: 10px;
  border: 2px solid oklch(100% 0 0 / 0.18);
  transition: transform 0.12s, border-color 0.12s;
}
.bd-swatch:hover .bd-swatch-face { transform: scale(1.05); }
.bd-swatch[aria-pressed="true"] .bd-swatch-face {
  border-color: var(--lg-accent, #6aa8ff);
  box-shadow: 0 0 0 3px oklch(65% 0.15 255 / 0.3);
}
.bd-swatch:focus-visible { outline: 2px solid var(--lg-accent, #6aa8ff); outline-offset: 2px; }
/* Mini previews — a static thumbnail of each design's palette. */
.bd-sw-aurora .bd-swatch-face { background: linear-gradient(130deg, #77e6c8, #7f9cf5 55%, #c78ae8); }
.bd-sw-nova   .bd-swatch-face { background: radial-gradient(circle at 35% 35%, #ffe9b8, #cfe6ff 70%, #fdfbf6); }
.bd-sw-void   .bd-swatch-face { background: radial-gradient(1.5px 1.5px at 25% 30%, #cdd8ff 40%, transparent 41%), radial-gradient(1px 1px at 68% 60%, #cdd8ff 40%, transparent 41%), radial-gradient(1.5px 1.5px at 45% 75%, #aab8f0 40%, transparent 41%), #020204; }
.bd-sw-silk   .bd-swatch-face { background: radial-gradient(circle at 25% 25%, #6a5cffcc, transparent 60%), radial-gradient(circle at 75% 75%, #0fb8a8cc, transparent 60%), #101422; }
.bd-sw-ocean  .bd-swatch-face { background: linear-gradient(#04121f 40%, #14507a 75%, #1d6ea3); }
.bd-sw-ember  .bd-swatch-face { background: radial-gradient(2px 2px at 30% 65%, #ffb050 40%, transparent 41%), radial-gradient(1.5px 1.5px at 62% 40%, #ff8040 40%, transparent 41%), #0c0605; }
.bd-sw-grid   .bd-swatch-face { background: repeating-linear-gradient(90deg, #5a8cff55 0 2px, transparent 2px 9px), repeating-linear-gradient(0deg, #5a8cff55 0 2px, transparent 2px 8px), linear-gradient(#03040a, #0b1030); }
.bd-sw-pulse  .bd-swatch-face { background: conic-gradient(from 40deg, #3a1c7a, #103a7a, #0c6b62, #3a1c7a); }

.bd-actions { display: flex; gap: 8px; }
.bd-act {
  flex: 1 1 0; min-height: 44px; border-radius: 12px; cursor: pointer;
  border: 1px solid oklch(100% 0 0 / 0.2); background: oklch(100% 0 0 / 0.08);
  color: inherit; font: inherit; font-size: 13px; font-weight: 650;
}
.bd-act:hover { background: oklch(100% 0 0 / 0.15); }
.bd-act:focus-visible { outline: 2px solid var(--lg-accent, #6aa8ff); outline-offset: 2px; }

@media (max-width: 380px) { .bd-grid { grid-template-columns: repeat(3, 1fr); } }
@media (prefers-reduced-motion: reduce) {
  #backdrop-css::before, #backdrop-css::after { animation: none !important; }
}