:root {
  --bg: #211311;
  --bg2: #3a1b16;
  --paper: #fbf3e5;
  --paper-soft: #fff9ee;
  --text: #f8eddd;
  --muted: #d8c3aa;
  --accent: #7d1f18;
  --accent-dark: #4c120f;
  --gold: #c69b55;
  --shadow: rgba(0, 0, 0, .45);
  --page-ratio: 1.41945; /* 1489 / 1049 */
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  min-height: 100%;
  background:
    radial-gradient(circle at top left, rgba(198,155,85,.2), transparent 28rem),
    linear-gradient(135deg, var(--bg), #100908 62%, var(--bg2));
  color: var(--text);
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

body { overflow-x: hidden; }

.app-shell {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.hero {
  width: min(1180px, 100%);
  margin: 0 auto;
  padding: 22px 18px 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.eyebrow {
  margin: 0 0 4px;
  font-size: 12px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--gold);
}

h1 {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(28px, 4vw, 46px);
  line-height: 1.05;
}

.subtitle {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 15px;
}

.top-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.btn {
  appearance: none;
  border: 1px solid rgba(198,155,85,.8);
  background: linear-gradient(180deg, #8d251e, #641813);
  color: #fff6e8;
  padding: 10px 16px;
  border-radius: 999px;
  font-weight: 700;
  letter-spacing: .01em;
  text-decoration: none;
  cursor: pointer;
  box-shadow: 0 8px 22px rgba(0,0,0,.18);
  transition: transform .15s ease, filter .15s ease, opacity .15s ease;
}

.btn:hover { transform: translateY(-1px); filter: brightness(1.08); }
.btn:active { transform: translateY(0); }
.btn:disabled { opacity: .45; cursor: not-allowed; transform: none; }
.btn-ghost { background: rgba(255,247,232,.09); }

.viewer-area {
  position: relative;
  flex: 1;
  display: grid;
  grid-template-columns: minmax(46px, 1fr) auto minmax(46px, 1fr);
  align-items: center;
  justify-items: center;
  gap: 10px;
  padding: 8px 14px 10px;
}

.book-stage {
  position: relative;
  width: min(94vw, 1000px);
  height: calc(min(94vw, 1000px) / 2 * var(--page-ratio));
  max-height: calc(100vh - 188px);
  max-width: calc((100vh - 188px) / var(--page-ratio) * 2);
  perspective: 2200px;
}

.book-shadow {
  position: absolute;
  inset: auto 4% -18px 4%;
  height: 38px;
  background: radial-gradient(ellipse at center, rgba(0,0,0,.55), transparent 70%);
  filter: blur(6px);
  pointer-events: none;
}

.book {
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  grid-template-columns: 1fr 1fr;
  transform-style: preserve-3d;
}

.page-slot {
  position: relative;
  height: 100%;
  background: var(--paper);
  overflow: hidden;
  box-shadow: 0 18px 52px var(--shadow);
}

.page-slot img, .flip-face img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
  background: var(--paper);
  user-select: none;
  -webkit-user-drag: none;
}

.page-left {
  border-radius: 10px 2px 2px 10px;
  transform-origin: right center;
}

.page-right {
  border-radius: 2px 10px 10px 2px;
  transform-origin: left center;
}

.page-left::after,
.page-right::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 28px;
  pointer-events: none;
  z-index: 2;
}

.page-left::after {
  right: 0;
  background: linear-gradient(90deg, transparent, rgba(0,0,0,.13));
}

.page-right::before {
  left: 0;
  background: linear-gradient(270deg, transparent, rgba(0,0,0,.13));
}

.page-empty {
  width: 100%;
  height: 100%;
  background:
    linear-gradient(90deg, rgba(0,0,0,.06), transparent 12%),
    var(--paper-soft);
}

.single-cover .book {
  grid-template-columns: 1fr;
  width: 50%;
  margin: 0 auto;
}

.single-cover .page-left { display: none; }
.single-cover .page-right { border-radius: 10px; }
.single-cover .page-right::before { display: none; }

.flip-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 20;
  display: none;
}

.flip-layer.active { display: block; }

.flip-leaf {
  position: absolute;
  top: 0;
  width: 50%;
  height: 100%;
  transform-style: preserve-3d;
  transition: transform 720ms cubic-bezier(.2,.75,.18,1);
  box-shadow: 0 18px 42px rgba(0,0,0,.28);
}

.flip-leaf.right {
  left: 50%;
  transform-origin: left center;
  border-radius: 2px 10px 10px 2px;
}

.flip-leaf.left {
  left: 0;
  transform-origin: right center;
  border-radius: 10px 2px 2px 10px;
}

.flip-leaf.right.turn { transform: rotateY(-180deg); }
.flip-leaf.left.turn { transform: rotateY(180deg); }

.flip-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  overflow: hidden;
  background: var(--paper);
}

.flip-face.back { transform: rotateY(180deg); }

.nav-arrow {
  width: 46px;
  height: 68px;
  border-radius: 999px;
  border: 1px solid rgba(198,155,85,.45);
  background: rgba(255,247,232,.08);
  color: #fff6e8;
  font-size: 48px;
  line-height: 1;
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: transform .15s ease, background .15s ease, opacity .15s ease;
}

.nav-arrow:hover { background: rgba(255,247,232,.16); transform: scale(1.04); }
.nav-arrow:disabled { opacity: .25; cursor: not-allowed; transform: none; }

.controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  padding: 10px 18px 8px;
}

.page-status {
  min-width: 185px;
  padding: 8px 16px;
  border: 1px solid rgba(198,155,85,.35);
  border-radius: 999px;
  background: rgba(255,247,232,.08);
  text-align: center;
}

.page-status strong {
  display: block;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 16px;
}

.page-status span {
  display: block;
  color: var(--muted);
  font-size: 13px;
  margin-top: 2px;
}

.hint {
  text-align: center;
  color: rgba(248,237,221,.72);
  font-size: 13px;
  padding: 2px 18px 14px;
}

@media (max-width: 760px) {
  .hero {
    align-items: flex-start;
    flex-direction: column;
    padding-top: 16px;
  }

  .top-actions { justify-content: flex-start; }

  .viewer-area {
    grid-template-columns: 1fr;
    padding-left: 10px;
    padding-right: 10px;
  }

  .nav-arrow { display: none; }

  .book-stage {
    width: min(96vw, 520px);
    height: calc(min(96vw, 520px) * var(--page-ratio));
    max-width: calc((100vh - 218px) / var(--page-ratio));
    max-height: calc(100vh - 218px);
  }

  .book, .single-cover .book {
    width: 100%;
    grid-template-columns: 1fr;
    margin: 0;
  }

  .page-left { display: none; }
  .page-right { border-radius: 10px; }
  .page-right::before { display: none; }

  .flip-leaf,
  .flip-leaf.left,
  .flip-leaf.right {
    left: 0;
    width: 100%;
    transform-origin: left center;
    border-radius: 10px;
  }

  .flip-leaf.left { transform-origin: right center; }
  .flip-leaf.right.turn { transform: rotateY(-180deg); }
  .flip-leaf.left.turn { transform: rotateY(180deg); }

  .controls {
    gap: 8px;
    padding: 8px 10px;
  }

  .controls .btn { padding: 9px 13px; }
  .page-status { min-width: 130px; padding: 7px 10px; }
  .hint { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .flip-leaf { transition: none; }
  .btn, .nav-arrow { transition: none; }
}

/* Cover mode: the first page is displayed as a single standalone cover. */
.single-cover .flip-leaf,
.single-cover .flip-leaf.right,
.single-cover .flip-leaf.left {
  left: 0;
  width: 100%;
  border-radius: 10px;
}