/* ─── BOOK DETAIL PAGE ─── */
.book-detail {
  position: relative;
  z-index: 1;
  max-width: 960px;
  margin: 0 auto;
  padding: 120px 48px 80px;
}

.book-detail-grid {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 48px;
  align-items: start;
}

.book-cover-frame {
  position: sticky;
  top: 100px;
  border-radius: var(--radius-xl);
  overflow: hidden;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow-lg);
  padding: 12px;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.book-cover-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: var(--radius-xl);
  background: linear-gradient(135deg, rgba(255,255,255,0.06) 0%, transparent 50%);
  pointer-events: none;
  z-index: 0;
}

.book-cover-frame img {
  width: 100%;
  display: block;
  border-radius: calc(var(--radius-xl) - 8px);
  position: relative;
  z-index: 1;
}

.book-info {
  padding-top: 8px;
}

.book-genre-tag {
  display: inline-block;
  padding: 5px 16px;
  border-radius: var(--radius-full);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 500;
  background: var(--amber-soft);
  color: var(--amber-light);
  margin-bottom: 20px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  border: 1px solid rgba(217, 119, 6, 0.12);
}

.book-info h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 3.5vw, 2.8rem);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 8px;
}

.book-info .book-author {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.book-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 28px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
}

.book-meta-dot {
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: var(--text-muted);
}

.book-description {
  font-size: 1.02rem;
  line-height: 1.85;
  color: var(--text-secondary);
  margin-bottom: 36px;
}

.book-actions {
  display: flex;
  gap: 12px;
  margin-bottom: 48px;
}

.book-actions .btn-primary,
.book-actions .btn-secondary {
  flex: 1;
  justify-content: center;
}

.book-add-btn.added {
  background: rgba(217, 119, 6, 0.15);
  border-color: rgba(217, 119, 6, 0.3);
  color: var(--amber-light);
}

.book-add-btn:disabled {
  cursor: default;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: color 200ms var(--ease-out);
}

.back-link:hover {
  color: var(--amber-light);
}

.back-link:active {
  transform: scale(0.97);
}

.back-link svg {
  transition: transform 200ms var(--ease-out);
}

.back-link:hover svg {
  transform: translateX(-3px);
}

/* ─── RELATED BOOKS ─── */
.related-section {
  position: relative;
  z-index: 1;
  padding: 64px 48px 80px;
  border-top: 1px solid var(--border);
}

.related-section h2 {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 32px;
  letter-spacing: -0.02em;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 20px;
}

.related-card {
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border);
  transition: transform 240ms var(--ease-out), border-color 240ms var(--ease-out);
  text-decoration: none;
  display: block;
}

.related-card:hover {
  transform: translateY(-4px);
  border-color: var(--glass-border-hover);
}

.related-card img {
  width: 100%;
  aspect-ratio: 2/3;
  object-fit: cover;
  display: block;
}

.related-card-info {
  padding: 12px;
}

.related-card-info h3 {
  font-family: var(--font-display);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 2px;
}

.related-card-info p {
  font-size: 0.72rem;
  color: var(--text-muted);
}

/* ─── RESPONSIVE ─── */
@media (max-width: 768px) {
  .book-detail {
    padding: 100px 24px 64px;
  }

  .book-detail-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .book-cover-frame {
    position: static;
    max-width: 280px;
    margin: 0 auto;
  }

  .book-actions {
    flex-direction: column;
  }

  .related-section {
    padding: 48px 24px 64px;
  }

  .related-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .book-detail {
    padding: 90px 16px 48px;
  }

  .book-cover-frame {
    max-width: 220px;
  }

  .related-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }
}