.book-detail-head {
  margin-bottom: 30px;
  padding: 28px 30px;
  border: 1px solid #e6e6e6;
  border-radius: 14px;
  background: rgba(255,255,255,.86);
}

.book-detail-kicker {
  margin-bottom: 8px;
  color: #49b1f5;
  font-size: .82em;
  font-weight: 700;
  letter-spacing: .06em;
}

.book-detail-title {
  margin-bottom: 7px;
  font-size: 1.72em;
  font-weight: 750;
  line-height: 1.5;
}

.book-detail-author {
  margin-bottom: 14px;
  font-size: .95em;
  opacity: .6;
}

.book-detail-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.book-detail-tag {
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(73,177,245,.10);
  color: #358cc4;
  font-size: .84em;
}

.book-summary-grid {
  display: grid;
  grid-template-columns: repeat(3,1fr);
  gap: 14px;
  margin: 22px 0 34px;
}

.book-summary-card {
  padding: 18px 19px;
  border: 1px solid #e6e6e6;
  border-radius: 10px;
  background: rgba(255,255,255,.84);
}

.book-summary-label {
  margin-bottom: 6px;
  color: #49b1f5;
  font-size: .78em;
  font-weight: 700;
}

.book-summary-value {
  line-height: 1.65;
  font-weight: 650;
}

.book-definition {
  margin: 23px 0;
  padding: 20px 22px;
  border-left: 4px solid #49b1f5;
  border-radius: 8px;
  background: rgba(73,177,245,.08);
  line-height: 1.9;
}

.book-question-grid {
  display: grid;
  grid-template-columns: repeat(2,1fr);
  gap: 16px;
  margin: 22px 0 34px;
}

.book-question-card {
  padding: 21px 23px;
  border: 1px solid #e6e6e6;
  border-radius: 10px;
  background: rgba(255,255,255,.84);
}

.book-question-card h3 {
  margin: 0 0 9px;
  font-size: 1.06em;
}

.book-question-card p {
  margin: 0;
  line-height: 1.82;
  opacity: .77;
}

.book-point-list {
  margin: 22px 0 34px;
}

.book-point {
  margin-bottom: 13px;
  padding: 18px 20px;
  border: 1px solid #e6e6e6;
  border-radius: 9px;
  background: rgba(255,255,255,.84);
  line-height: 1.85;
}

.book-point strong {
  color: #358cc4;
}

.book-warning {
  margin: 23px 0;
  padding: 20px 22px;
  border-radius: 10px;
  background: rgba(0,0,0,.04);
  line-height: 1.9;
}

.book-reading-note {
  margin: 23px 0;
  padding: 22px 24px;
  border-radius: 10px;
  background: rgba(0,0,0,.035);
  line-height: 1.9;
}

.book-related-grid {
  display: grid;
  grid-template-columns: repeat(2,1fr);
  gap: 14px;
  margin: 22px 0 30px;
}

.book-related-card,
.book-related-card:visited {
  display: block;
  padding: 18px 20px;
  border: 1px solid #e5e5e5;
  border-radius: 9px;
  background: rgba(255,255,255,.84);
  color: inherit !important;
  text-decoration: none !important;
  transition: .2s ease;
}

.book-related-card:hover {
  transform: translateY(-2px);
  border-color: #49b1f5;
}

.book-related-type {
  margin-bottom: 6px;
  color: #49b1f5;
  font-size: .78em;
  font-weight: 700;
}

.book-related-title {
  font-weight: 700;
}

.book-related-desc {
  margin-top: 6px;
  font-size: .88em;
  line-height: 1.7;
  opacity: .67;
}

.book-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin: 28px 0;
}

.book-nav-link,
.book-nav-link:visited {
  padding: 9px 14px;
  border: 1px solid #ddd;
  border-radius: 8px;
  color: inherit !important;
  text-decoration: none !important;
}

.book-nav-link:hover {
  border-color: #49b1f5;
}

.book-update {
  margin-top: 28px;
  padding-top: 15px;
  border-top: 1px solid #e8e8e8;
  font-size: .86em;
  opacity: .6;
}

@media (max-width: 768px) {
  .book-summary-grid,
  .book-question-grid,
  .book-related-grid {
    grid-template-columns: 1fr;
  }

  .book-detail-head {
    padding: 22px 20px;
  }

  .book-detail-title {
    font-size: 1.45em;
  }

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