/* Album book body. Clicks stay on #book-stage and the two page buttons. */
.book-stage {
  perspective: 1700px;
  display: flex;
  justify-content: center;
  padding: 0.2rem 0 0.6rem;
}

.album-book {
  position: relative;
  width: min(100%, 540px);
  transform: rotateY(-6deg) rotateX(3deg);
  transform-style: preserve-3d;
}

.album-spine,
.album-stack {
  pointer-events: none;
}

.album-spine {
  position: absolute;
  left: -10px;
  top: 10px;
  bottom: 10px;
  width: 11px;
  border-radius: 3px 0 0 3px;
  background: linear-gradient(90deg, #9aa8b8, #c5d0dc 55%, #b7c2cf);
  box-shadow: inset -1px 0 0 rgba(255, 255, 255, 0.35);
  z-index: 3;
}

.album-stack {
  position: absolute;
  inset: 12px -7px 12px 4px;
  border-radius: 2px 10px 10px 2px;
  background: repeating-linear-gradient(90deg, #d7dee7 0 1px, #f4f1ea 1px 3px);
  box-shadow: 10px 16px 28px rgba(58, 68, 80, 0.12);
  z-index: 0;
}

.album-block {
  position: relative;
  z-index: 2;
  transform-style: preserve-3d;
}

#book-page.page {
  transform-origin: left center;
  background:
    linear-gradient(90deg, rgba(138, 155, 176, 0.14), transparent 16px),
    var(--paper);
}

#book-page.page.is-letter {
  padding: 1.6rem 1.5rem 1.7rem 1.7rem;
  min-height: 320px;
}

#book-page.page.is-letter h2 {
  text-align: center;
  font-size: 1.7rem;
  color: var(--maple);
  margin-bottom: 0.35rem;
}

#book-page.page.is-letter p {
  margin: 0.85rem 0;
  line-height: 2;
  font-size: 1.05rem;
  text-align: justify;
}

#book-page.page.is-letter .dedication {
  text-align: center;
  color: var(--ink);
  border-top: 1px dashed #c5d0dc;
  padding-top: 0.9rem;
  margin-top: 1.1rem;
}

#book-page.page.is-turn-next {
  animation: book-turn-next 0.92s cubic-bezier(0.22, 0.61, 0.36, 1);
}

#book-page.page.is-turn-prev {
  animation: book-turn-prev 0.92s cubic-bezier(0.22, 0.61, 0.36, 1);
}

@keyframes book-turn-next {
  0% { transform: rotateY(0deg) translateZ(0); }
  18% { transform: rotateY(-16deg) translateZ(14px); }
  46% { transform: rotateY(-88deg) translateZ(26px); }
  54% { transform: rotateY(88deg) translateZ(18px); opacity: 0.92; }
  82% { transform: rotateY(10deg) translateZ(8px); opacity: 1; }
  100% { transform: rotateY(0deg) translateZ(0); }
}

@keyframes book-turn-prev {
  0% { transform: rotateY(0deg) translateZ(0); }
  18% { transform: rotateY(16deg) translateZ(14px); }
  46% { transform: rotateY(88deg) translateZ(26px); }
  54% { transform: rotateY(-88deg) translateZ(18px); opacity: 0.92; }
  82% { transform: rotateY(-10deg) translateZ(8px); opacity: 1; }
  100% { transform: rotateY(0deg) translateZ(0); }
}

.motif.is-pop .i {
  animation: motif-pop 0.55s ease;
}

@keyframes motif-pop {
  0% { transform: scale(1); opacity: 0.42; }
  40% { transform: scale(1.35); opacity: 0.9; }
  100% { transform: scale(1); opacity: 0.7; }
}

.motif-bit {
  pointer-events: none;
  position: fixed;
  z-index: 6;
  font-size: 0.7rem;
  opacity: 0.7;
  animation: motif-fly 0.85s ease forwards;
}

@keyframes motif-fly {
  to {
    transform: translate3d(var(--mx, 20px), -36px, 0);
    opacity: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  #book-page.page.is-turn-next,
  #book-page.page.is-turn-prev,
  .motif.is-pop .i,
  .motif-bit {
    animation: none;
  }
}