/* Blaetter-Buch fuer die Academy-Kataloge.
   Aufbau pro Seite:
   .book[data-book][data-pages][data-prefix][data-pdf]
   > .book__bar (Toolbar) + .book__stage > .spread + Zonen + .book__strip
   Querformat-Seiten: Standard = Einzelseite gross, optional Doppelseite. */

.book {
  margin: var(--gap) 0 clamp(1.2rem, 1rem + 2vw, 2rem);
  max-width: 72rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: color-mix(in oklab, var(--bg-raise) 85%, transparent);
  box-shadow:
    0 0 0 1px color-mix(in oklab, var(--cyan) 18%, transparent),
    0 24px 60px -40px color-mix(in oklab, var(--cyan) 60%, transparent);
}

.book__bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 0.5rem;
  padding: 0.5rem 0.6rem;
  background: rgb(4 6 9 / 0.92);
  border-bottom: 1px solid var(--line-soft);
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: var(--step--1);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.book__btn,
.book__link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  min-height: 2rem;
  padding: 0.25rem 0.6rem;
  font: inherit;
  letter-spacing: inherit;
  text-transform: inherit;
  text-decoration: none;
  color: var(--ink-dim);
  background: transparent;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  cursor: pointer;
  transition: color 0.15s var(--ease), border-color 0.15s var(--ease),
    background-color 0.15s var(--ease);
  white-space: nowrap;
}

.book__btn:hover,
.book__link:hover {
  color: var(--bg);
  background: var(--cyan);
  border-color: var(--cyan);
}

.book__btn:focus-visible,
.book__link:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.book__btn[aria-pressed="true"] {
  color: var(--bg);
  background: var(--cyan);
  border-color: var(--cyan);
}

.book__page {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--ink-dim);
  padding-inline: 0.2rem;
}

.book__page input {
  width: 3.6rem;
  padding: 0.25rem 0.3rem;
  font: inherit;
  text-align: center;
  color: var(--ink);
  background: var(--bg-raise);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
}

.book__page input:focus {
  border-color: var(--cyan);
  outline: none;
}

.book__spacer {
  flex: 1 1 auto;
}

/* --- Buehne -------------------------------------------------------- */

.book__stage {
  position: relative;
  display: flex;
  justify-content: center;
  padding: clamp(1rem, 0.6rem + 2vw, 2rem);
  background:
    radial-gradient(120% 90% at 50% 0%, rgb(34 211 238 / 0.08), transparent 55%),
    linear-gradient(180deg, #141a21, #0a0d12);
  overflow: hidden;
}

.spread {
  position: relative;
  display: flex;
  width: min(100%, 62rem);
  perspective: 2600px;
  filter: drop-shadow(0 30px 50px rgb(0 0 0 / 0.55));
}

.book[data-mode="single"] .spread {
  width: min(100%, 38rem);
}

.sheet {
  position: relative;
  margin: 0;
  flex: 1 1 0;
  min-width: 0;
  background: #f4f1e8;
  overflow: hidden;
}

.book[data-mode="single"] .sheet--left {
  display: none;
}

.sheet--left {
  border-radius: 8px 2px 2px 8px;
  border-right: 1px solid rgb(0 0 0 / 0.18);
  background-image: linear-gradient(to right, rgb(0 0 0 / 0.14), transparent 7%);
}

.sheet--right {
  border-radius: 2px 8px 8px 2px;
  background-image: linear-gradient(to left, rgb(0 0 0 / 0.14), transparent 7%);
}

.book[data-mode="spread"] .sheet--left::after,
.book[data-mode="spread"] .sheet--right::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 9%;
  pointer-events: none;
}

.book[data-mode="spread"] .sheet--left::after {
  right: 0;
  background: linear-gradient(to left, rgb(0 0 0 / 0.28), transparent);
}

.book[data-mode="spread"] .sheet--right::before {
  left: 0;
  z-index: 2;
  background: linear-gradient(to right, rgb(0 0 0 / 0.28), transparent);
}

.sheet img {
  display: block;
  width: 100%;
  height: auto;
  background: #f4f1e8;
  user-select: none;
  -webkit-user-drag: none;
}

.sheet figcaption {
  position: absolute;
  bottom: 0.35rem;
  font-family: ui-monospace, Menlo, Consolas, monospace;
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  color: rgb(0 0 0 / 0.45);
}

.sheet--left figcaption {
  left: 0.7rem;
}

.sheet--right figcaption {
  right: 0.7rem;
}

/* Das umblaetternde Blatt: liegt ueber der rechten (vor) bzw. linken
   (zurueck) Haelfte, dreht sich um den Bund in der Mitte. */
.leaf {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 50%;
  transform-style: preserve-3d;
  pointer-events: none;
  opacity: 0;
}

.leaf[data-side="right"] {
  left: 50%;
  transform-origin: left center;
}

.leaf[data-side="left"] {
  left: 0;
  transform-origin: right center;
}

.book[data-mode="single"] .leaf {
  left: 0;
  width: 100%;
  transform-origin: left center;
}

.leaf__face {
  position: absolute;
  inset: 0;
  overflow: hidden;
  background: #f4f1e8;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.leaf__face img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.book[data-mode="spread"] .leaf__face--front {
  border-radius: 2px 8px 8px 2px;
}

.book[data-mode="spread"] .leaf__face--back {
  transform: rotateY(180deg);
  border-radius: 8px 2px 2px 8px;
}

.leaf[data-side="left"] .leaf__face--front {
  transform: rotateY(180deg);
}

.leaf[data-side="left"] .leaf__face--back {
  transform: rotateY(0deg);
}

.leaf.is-anim {
  opacity: 1;
  transition: transform 0.65s cubic-bezier(0.35, 0.1, 0.25, 1);
}

.leaf[data-side="right"].is-anim {
  transform: rotateY(-180deg);
}

.leaf[data-side="left"].is-anim {
  transform: rotateY(180deg);
}

.leaf.is-anim::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(to right, transparent 60%, rgb(0 0 0 / 0.25));
  animation: leafshade 0.65s ease;
}

@keyframes leafshade {
  50% {
    background: linear-gradient(to right, transparent 20%, rgb(0 0 0 / 0.35));
  }
}

/* Klickzonen links/rechts */
.zone {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 15%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.2rem;
  line-height: 1;
  color: transparent;
  background: transparent;
  border: 0;
  cursor: pointer;
  transition: color 0.2s var(--ease);
}

.zone:hover,
.zone:focus-visible {
  color: var(--cyan);
}

.zone--prev {
  left: 0;
}

.zone--next {
  right: 0;
}

.book__loading,
.book__error {
  position: absolute;
  inset: auto 1rem 1rem;
  margin: 0 auto;
  width: fit-content;
  padding: 0.4rem 0.9rem;
  font-family: ui-monospace, Menlo, Consolas, monospace;
  font-size: var(--step--1);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-dim);
  background: rgb(4 6 9 / 0.9);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
}

.book__error a {
  color: var(--cyan);
}

/* --- Filmstreifen --------------------------------------------------- */

.book__strip {
  display: flex;
  gap: 0.4rem;
  overflow-x: auto;
  padding: 0.6rem;
  background: rgb(4 6 9 / 0.92);
  border-top: 1px solid var(--line-soft);
  scrollbar-width: thin;
}

.book__thumb {
  flex: 0 0 auto;
  width: 4.2rem;
  padding: 0;
  background: #f4f1e8;
  border: 2px solid transparent;
  border-radius: 3px;
  overflow: hidden;
  cursor: pointer;
}

.book__thumb img {
  display: block;
  width: 100%;
  height: auto;
}

.book__thumb[aria-current="true"] {
  border-color: var(--cyan);
}

.book__thumb:hover {
  border-color: var(--cyan-soft);
}

.book__hint {
  margin: 0;
  padding: 0.5rem 0.8rem;
  font-size: var(--step--1);
  color: var(--ink-faint);
  border-top: 1px solid var(--line-soft);
}

.book__hint a {
  color: var(--ink-dim);
}

.book:fullscreen {
  max-width: none;
  margin: 0;
  border-radius: 0;
  overflow-y: auto;
}

.book:fullscreen .spread {
  width: min(100%, 90rem);
}

.book[data-mode="single"]:fullscreen .spread {
  width: min(100%, 52rem);
}

@media (max-width: 40rem) {
  .book__spacer {
    display: none;
  }

  .zone {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .leaf.is-anim {
    transition: none;
  }
}

@media print {
  .book__bar,
  .book__strip,
  .book__hint,
  .zone {
    display: none;
  }
}