:root {
  --bg: #ece6d9;
  --panel: #f8f3e9;
  --ink: #2a241c;
  --muted: #756c60;
  --btn: #f4ede0;
  --btn-border: #baa88b;
  --shadow: rgba(0,0,0,0.22);
  --book-shadow: rgba(0,0,0,0.18);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  background: radial-gradient(circle at top, #f4efe4, #ddd4c3 75%);
  color: var(--ink);
  font: 16px/1.35 Georgia, "Times New Roman", serif;
}

.viewer-shell {
  min-height: 100%;
  display: flex;
  flex-direction: column;
}

.toolbar {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: center;
  padding: 0.8rem 1rem;
  background: rgba(255,255,255,0.72);
  backdrop-filter: blur(4px);
  border-bottom: 1px solid rgba(0,0,0,0.08);
  position: sticky;
  top: 0;
  z-index: 20;
}

.toolbar-title {
  display: flex;
  flex-direction: column;
}
.subtitle {
  font-size: 0.92rem;
  color: var(--muted);
}

.toolbar-controls {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.45rem;
}

button,
.close-link {
  border: 1px solid var(--btn-border);
  background: var(--btn);
  color: var(--ink);
  border-radius: 8px;
  padding: 0.45rem 0.8rem;
  font: inherit;
  cursor: pointer;
}
.close-link {
  text-decoration: none;
  display: inline-block;
}
button:hover,
.close-link:hover { filter: brightness(0.98); }
button:disabled { opacity: 0.45; cursor: default; }
.divider {
  width: 1px;
  height: 1.8rem;
  background: rgba(0,0,0,0.15);
  display: inline-block;
}

.stage-wrap {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 1.2rem;
  overflow: auto;
}

.book-stage {
  position: relative;
  width: min(92vw, 1220px);
  aspect-ratio: 1000 / 707;
  transform-origin: center center;
  transition: transform 0.2s ease;
}

.zoom-90 { transform: scale(0.9); }
.zoom-100 { transform: scale(1); }
.zoom-115 { transform: scale(1.15); }
.zoom-130 { transform: scale(1.30); }
.zoom-150 { transform: scale(1.50); }

.book-base {
  position: absolute;
  inset: 0;
  display: grid;
  grid-template-columns: 1fr 12px 1fr;
  background: linear-gradient(90deg, #d8ccb6 0%, #e8dfcf 10%, #f4edde 18%, #f5f0e5 50%, #f4edde 82%, #e8dfcf 90%, #d8ccb6 100%);
  border-radius: 10px;
  box-shadow: 0 20px 38px var(--book-shadow);
  overflow: hidden;
}

.page-panel {
  position: relative;
  background: #f8f3e9;
  overflow: hidden;
}

.page-panel img,
.sheet-face img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
  background: var(--panel);
}

.page-panel.blank::before,
.sheet-face.blank::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(90deg, rgba(0,0,0,0.03), rgba(255,255,255,0.2), rgba(0,0,0,0.03));
}

.spine {
  background: linear-gradient(90deg, rgba(69,53,33,0.25), rgba(255,255,255,0.5), rgba(69,53,33,0.22));
  box-shadow: inset 0 0 12px rgba(0,0,0,0.08);
}



/* Closed-book states: no phantom page on the unused side. */
.book-base.single-right,
.book-base.single-left {
  background: transparent;
  box-shadow: none;
  overflow: visible;
}

.book-base.single-right .spine,
.book-base.single-left .spine {
  background: transparent;
  box-shadow: none;
}

.book-base.single-right .left-panel,
.book-base.single-left .right-panel {
  background: transparent;
  box-shadow: none;
}

.book-base.single-right .left-panel.blank::before,
.book-base.single-left .right-panel.blank::before {
  display: none;
}

.book-base.single-right .right-panel,
.book-base.single-left .left-panel {
  box-shadow: 0 20px 38px var(--book-shadow);
}

.transition-clone {
  z-index: 6;
  pointer-events: none;
}


.turn-overlay {
  position: absolute;
  inset: 0;
  pointer-events: none;
  perspective: 2200px;
}
.turn-overlay.hidden { display: none; }

.turn-sheet {
  position: absolute;
  top: 0;
  bottom: 0;
  width: calc((100% - 12px) / 2);
  transform-style: preserve-3d;
}
.turn-sheet.forward { right: 0; transform-origin: left center; }
.turn-sheet.backward { left: 0; transform-origin: right center; }

.sheet-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  overflow: hidden;
  background: #f8f3e9;
  box-shadow: 0 10px 24px var(--shadow);
}
.sheet-face.back { transform: rotateY(180deg); }

.turn-sheet.forward.animating {
  animation: turnForward 0.75s ease-in-out forwards;
}
.turn-sheet.backward.animating {
  animation: turnBackward 0.75s ease-in-out forwards;
}

@keyframes turnForward {
  0% { transform: rotateY(0deg); box-shadow: 0 0 0 rgba(0,0,0,0); }
  50% { box-shadow: -28px 8px 22px rgba(0,0,0,0.22); }
  100% { transform: rotateY(-180deg); box-shadow: 0 0 0 rgba(0,0,0,0); }
}

@keyframes turnBackward {
  0% { transform: rotateY(0deg); box-shadow: 0 0 0 rgba(0,0,0,0); }
  50% { box-shadow: 28px 8px 22px rgba(0,0,0,0.22); }
  100% { transform: rotateY(180deg); box-shadow: 0 0 0 rgba(0,0,0,0); }
}

.footer-note {
  padding: 0.7rem 1rem 1rem;
  color: var(--muted);
  text-align: center;
}

@media (max-width: 900px) {
  .toolbar {
    flex-direction: column;
    align-items: flex-start;
  }
  .book-stage {
    width: min(96vw, 820px);
  }
}

@media (max-width: 640px) {
  .toolbar-controls {
    gap: 0.35rem;
  }
  button {
    padding: 0.35rem 0.6rem;
  }
  .book-stage {
    width: min(98vw, 640px);
  }
}