/* Flipbook styles */
.fb-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin: 3rem 0 2rem;
  outline: none;
}
.fb-book {
  position: relative;
  width: min(88vw, 980px);
  aspect-ratio: calc(2 * var(--fb-ratio, .75)) / 1;
  perspective: 2600px;
  transform-style: preserve-3d;
  transition: transform .8s cubic-bezier(.2,.7,.2,1);
}
/* closed book sits centered on its single visible page */
.fb-book.at-cover { transform: translateX(-25%); }
.fb-book.at-end   { transform: translateX(25%); }

.fb-leaf {
  position: absolute;
  left: 50%; top: 0;
  width: 50%; height: 100%;
  transform-origin: left center;
  transform-style: preserve-3d;
  transition: transform .75s cubic-bezier(.3,.1,.25,1);
  cursor: pointer;
}
.fb-leaf.flipped { transform: rotateY(-180deg); }

.fb-page {
  position: absolute; inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  background: #fdfcf8;
  overflow: hidden;
  box-shadow: 0 6px 30px rgba(0,0,0,.45);
}
.fb-back { transform: rotateY(180deg); }
.fb-page img {
  width: 100%; height: 100%;
  object-fit: contain;
  background: #fdfcf8;
  user-select: none;
}
.fb-page.fb-blank { background: #fdfcf8; }   /* a real blank leaf, not a hole */

/* moving page shading for depth */
.fb-shade {
  position: absolute; inset: 0;
  pointer-events: none;
  transition: opacity .75s;
  opacity: .16;
}
.fb-front .fb-shade { background: linear-gradient(90deg, rgba(0,0,0,.32), transparent 22%); }
.fb-back  .fb-shade { background: linear-gradient(-90deg, rgba(0,0,0,.32), transparent 22%); }

.fb-controls {
  display: flex; align-items: center; gap: 1.6rem;
  margin-top: 1.6rem;
}
.fb-btn {
  background: none;
  border: 1px solid var(--accent);
  color: var(--ink);
  width: 46px; height: 46px;
  border-radius: 50%;
  font-size: 1.5rem; line-height: 1;
  cursor: pointer;
  transition: background .3s, color .3s, transform .3s;
}
.fb-btn:hover { background: var(--accent); color: #000; transform: scale(1.1); }
.fb-count {
  font-size: .72rem; letter-spacing: .3em; text-transform: uppercase;
  color: var(--muted);
  min-width: 12ch; text-align: center;
}
@media (max-width: 640px) {
  .fb-book { width: 94vw; }
  .fb-book.at-cover { transform: translateX(-24%) scale(1.0); }
}