.hero {
  padding: 2rem;
  border-radius: 12px;
  background: #f4f8fb;
  margin-bottom: 1.5rem;
}
.callout-important {
  border-left: 5px solid #0d6efd;
}
.schedule-table td, .schedule-table th {
  vertical-align: top;
}

/* KEEP EVERYTHING ELSE (especially body font) UNCHANGED */

/* chapter container stays neutral */
.chapter-list {
  max-width: 900px;
  margin-top: 20px;
}

/* FLOATING CHAPTER BLOCK (no font changes) */
.chapter {
  border: 1px solid rgba(17, 24, 39, 0.08);
  border-left: 4px solid rgba(59, 130, 246, 0.35);

  border-radius: 12px;

  margin-bottom: 12px;

  background: white;

  box-shadow: 0 1px 4px rgba(0,0,0,0.04);

  transition: all 0.2s ease;
}

/* hover = subtle lift only */
.chapter:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.06);
  border-left: 4px solid rgba(59, 130, 246, 0.6);
}

/* IMPORTANT: do NOT touch font family here */
.chapter summary {
  cursor: pointer;
  list-style: none;

  font-size: 16px;
  font-weight: 600;
  color: #111827;

  display: flex;
  justify-content: space-between;
  align-items: center;

  padding: 12px 14px;

  border-radius: 12px;
}

/* hover highlight only */
.chapter summary:hover {
  background: rgba(59, 130, 246, 0.05);
}

/* remove default arrow */
.chapter summary::-webkit-details-marker {
  display: none;
}

/* expanded content (no font changes, inherit everything) */
.chapter-content {
  margin: 10px 14px 14px 14px;

  font-size: 14px;
  line-height: 1.6;

  color: #374151;

  background: rgba(248, 250, 252, 0.9);

  border: 1px solid rgba(17, 24, 39, 0.06);
  border-radius: 10px;

  padding: 12px 14px;
}

/* tag stays untouched visually */
.tag {
  font-size: 12px;
  color: #6b7280;
  font-weight: 400;
}