/* Dysun Energy brochure-flipbook — goud op zwart, zelfstandig (geen externe assets) */
* { margin: 0; padding: 0; box-sizing: border-box; }
html, body { height: 100%; }
body {
  background: #0a0a0a;
  color: #fff;
  font-family: Inter, "Segoe UI", system-ui, -apple-system, sans-serif;
  overflow: hidden;
  -webkit-tap-highlight-color: transparent;
}
#fb {
  position: fixed; inset: 0;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  gap: 14px; padding: 16px 12px 10px;
}
.stage { perspective: 2600px; flex: 0 0 auto; }
.book {
  position: relative;
  transform-style: preserve-3d;
  transition: transform .7s cubic-bezier(.4, .1, .2, 1);
  filter: drop-shadow(0 18px 40px rgba(0, 0, 0, .55));
}
.leaf {
  position: absolute; top: 0; left: 50%;
  width: 50%; height: 100%;
  transform-origin: 0% 50%;
  transform-style: preserve-3d;
  transition: transform .7s cubic-bezier(.4, .1, .2, 1);
}
.leaf.flipped { transform: rotateY(-180deg); }
.face {
  position: absolute; inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  overflow: hidden;
  background: #141414;
}
.face img {
  width: 100%; height: 100%; display: block;
  object-fit: cover;
  user-select: none; -webkit-user-drag: none;
}
.face.back { transform: rotateY(180deg); }
/* rugschaduw bij de vouw */
.face.front::after, .face.back::after {
  content: ""; position: absolute; top: 0; bottom: 0; width: 7%;
  pointer-events: none;
}
.face.front::after { left: 0; background: linear-gradient(90deg, rgba(0,0,0,.28), rgba(0,0,0,0)); }
.face.back::after { right: 0; background: linear-gradient(270deg, rgba(0,0,0,.24), rgba(0,0,0,0)); }

.bar {
  display: flex; align-items: center; gap: 18px;
  flex: 0 0 auto;
}
.nav {
  width: 42px; height: 42px; border-radius: 50%;
  border: 1px solid rgba(253, 197, 0, .45);
  background: rgba(253, 197, 0, .06);
  color: #FDC500; font-size: 18px; line-height: 1;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: background .15s, transform .15s;
}
.nav:hover { background: rgba(253, 197, 0, .16); transform: scale(1.06); }
.nav:disabled { opacity: .25; cursor: default; transform: none; }
.counter {
  min-width: 92px; text-align: center;
  font-size: 12.5px; letter-spacing: .14em;
  color: rgba(255, 255, 255, .78);
  font-variant-numeric: tabular-nums;
}
.counter b { color: #FDC500; font-weight: 600; }
.expand {
  position: fixed; top: 12px; right: 12px;
  width: 36px; height: 36px; border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, .18);
  background: rgba(255, 255, 255, .05);
  color: rgba(255, 255, 255, .85); font-size: 15px;
  cursor: pointer; display: flex; align-items: center; justify-content: center;
  text-decoration: none;
  transition: border-color .15s, color .15s;
}
.expand:hover { border-color: #FDC500; color: #FDC500; }
@media (prefers-reduced-motion: reduce) {
  .leaf, .book { transition: none; }
}