/* ==========================================================================
   Livre 3D — feuilletage réaliste, rotation, zoom, modes à plat.
   Structure : .book3d-stage > .book3d-world > .book3d-book > .book3d-leaf ×N
   ========================================================================== */

.book3d-stage {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: 320px;
  perspective: 2200px;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  cursor: grab;
}
.book3d-stage.is-dragging { cursor: grabbing; }

/* Ombre portée au sol */
.book3d-stage::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 6%;
  width: 46%;
  height: 5%;
  transform: translateX(-50%);
  background: radial-gradient(ellipse at center, rgba(31, 41, 51, .22), transparent 70%);
  filter: blur(6px);
  pointer-events: none;
}

.book3d-world {
  transform-style: preserve-3d;
  transition: transform .5s var(--ease, ease);
  will-change: transform;
}
.book3d-stage.is-dragging .book3d-world { transition: none; }

.book3d-book {
  position: relative;
  height: var(--book-h, 420px);
  aspect-ratio: 296 / 210;             /* double page A5 */
  transform-style: preserve-3d;
  transition: transform .9s var(--ease, ease);
}

.book3d-leaf {
  position: absolute;
  left: 50%;
  top: 0;
  width: 50%;
  height: 100%;
  transform-origin: left center;
  transform-style: preserve-3d;
  transition: transform .9s cubic-bezier(.45, .05, .3, 1);
}
.book3d-leaf.is-flipped { transform: rotateY(-180deg); }

.book3d-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  overflow: hidden;
  background: #fff;
}
.book3d-face .lv-page { height: 100%; width: 100%; }
.book3d-face--back { transform: rotateY(180deg); }

/* Ombre de pli, côté reliure */
.book3d-face--front::after,
.book3d-face--back::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  transition: opacity .9s ease;
}
.book3d-face--front::after {
  background: linear-gradient(to right, rgba(31,25,12,.16), rgba(31,25,12,.035) 12%, transparent 22%);
}
.book3d-face--back::after {
  background: linear-gradient(to left, rgba(31,25,12,.16), rgba(31,25,12,.035) 12%, transparent 22%);
}

/* Couverture : léger cadre + épaisseur perçue */
.book3d-leaf--cover .book3d-face {
  box-shadow: 0 0 0 1px rgba(31, 25, 12, .12), 0 10px 30px -12px rgba(31, 41, 51, .35);
}

/* Tranche des pages (épaisseur du bloc) */
.book3d-edge {
  position: absolute;
  top: .6%;
  bottom: .6%;
  width: 10px;
  right: 0;
  transform-origin: right center;
  background:
    repeating-linear-gradient(to right, #F6F2E9 0 1.6px, #DDD6C6 1.6px 2px);
  border-radius: 0 2px 2px 0;
  pointer-events: none;
  opacity: 0;
  transition: opacity .4s ease;
}
.book3d-edge.is-visible { opacity: 1; }

/* ---------------- Modes à plat (double page / page à page) ---------------- */

.book3d-flat {
  position: absolute;
  inset: 0;
  overflow: auto;
  display: none;
  padding: var(--sp-5, 24px);
  scrollbar-width: thin;
}
.book3d-flat-inner {
  margin: auto;
  display: flex;
  gap: 2px;
  justify-content: center;
  align-items: center;
  transform-origin: top center;
  min-height: 100%;
}
.book3d-flat-inner .lv-page {
  width: var(--flat-page-w, 340px);
  box-shadow: var(--shadow, 0 6px 24px -8px rgba(31,41,51,.16));
  flex: none;
}

.book3d-stage[data-mode="double"],
.book3d-stage[data-mode="simple"] {
  perspective: none;
  cursor: default;
  touch-action: pan-x pan-y;
}
.book3d-stage[data-mode="double"] .book3d-world,
.book3d-stage[data-mode="simple"] .book3d-world,
.book3d-stage[data-mode="double"]::after,
.book3d-stage[data-mode="simple"]::after { display: none; }
.book3d-stage[data-mode="double"] .book3d-flat,
.book3d-stage[data-mode="simple"] .book3d-flat { display: block; }

@media (prefers-reduced-motion: reduce) {
  .book3d-leaf, .book3d-book, .book3d-world { transition-duration: .01ms !important; }
}