.book-page {
  background: linear-gradient(135deg, #1a2436 0%, #0a1320 100%);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  color: #e8edf5;
}

.book-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-5);
  background: rgba(0,0,0,0.25);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.book-topbar__brand {
  display: inline-flex; align-items: center; gap: var(--space-3);
  color: #fff; text-decoration: none;
  font-family: var(--f-display); font-size: 1.2rem; letter-spacing: 0.04em;
}
.book-topbar__brand .nav__brand-mark { box-shadow: 0 0 0 4px rgba(200,16,46,0.3); }
.book-topbar__title {
  font-family: var(--f-display);
  font-size: 1.4rem;
  letter-spacing: 0.06em;
  color: #fff;
}
.book-topbar__back {
  color: #cdd5e2;
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 14px;
  border-radius: 999px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.12);
  transition: background var(--t-fast);
}
.book-topbar__back:hover { background: rgba(255,255,255,0.16); color: #fff; }

.book-stage {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-5);
  position: relative;
  overflow: hidden;
}

#book {
  margin: 0 auto;
  box-shadow: 0 30px 80px rgba(0,0,0,0.6), 0 10px 30px rgba(0,0,0,0.4);
}

.book-page-img {
  background: #fff;
  background-size: cover;
  background-position: center;
  width: 100%;
  height: 100%;
  display: block;
}

.book-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-4);
  padding: var(--space-4);
  background: rgba(0,0,0,0.25);
  backdrop-filter: blur(8px);
  border-top: 1px solid rgba(255,255,255,0.06);
}
.book-btn {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid rgba(255,255,255,0.18);
  background: rgba(255,255,255,0.08);
  color: #fff;
  cursor: pointer;
  font-size: 1.4rem;
  display: grid;
  place-items: center;
  transition: background var(--t-fast), transform var(--t-fast);
}
.book-btn:hover { background: rgba(255,255,255,0.18); transform: translateY(-2px); }
.book-btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }
.book-progress {
  font-family: var(--f-display);
  font-size: 1.2rem;
  letter-spacing: 0.06em;
  color: #fff;
  min-width: 80px;
  text-align: center;
}
.book-hint {
  text-align: center;
  font-size: 0.85rem;
  color: #8d97a8;
  padding: 0 var(--space-4) var(--space-3);
}

@media (max-width: 600px) {
  .book-topbar { flex-wrap: wrap; gap: var(--space-2); padding: var(--space-3); }
  .book-topbar__title { font-size: 1.1rem; order: 3; width: 100%; text-align: center; }
  .book-stage { padding: var(--space-3); }
}