.hero-subtitle {
  max-width: 42ch;
}

.catalog-runline {
  margin: 0.75rem 0 0;
  color: var(--text-soft);
  font-family: var(--mono);
  font-size: 0.76rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.catalog-group-card,
.offerings-card {
  scroll-margin-top: 5.6rem;
}

.catalog-group-card,
.offerings-card {
  background: var(--panel);
}

.catalog-group-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.learn-tabs {
  margin-top: 0.8rem;
  background: var(--panel);
}

.offerings-card {
  border-color: color-mix(in srgb, var(--border) 82%, var(--accent-2));
}

.offerings-summary {
  display: grid;
  gap: 0.75rem;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  margin-top: 0.9rem;
}

.offering-stat,
.offering-group {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.03);
}

.offering-stat {
  padding: 0.8rem 0.9rem;
}

.offering-stat strong {
  display: block;
  font-family: var(--mono);
  font-size: 0.96rem;
  line-height: 1;
  color: var(--accent-2);
  letter-spacing: 0.03em;
}

.offering-stat span {
  display: block;
  margin-top: 0.4rem;
  color: var(--text-dim);
  font-size: 0.8rem;
  line-height: 1.4;
}

.offerings-grid {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
}

.offering-group {
  padding: 0.95rem 1rem;
}

.offering-group-title {
  margin: 0;
  font-size: 0.98rem;
  line-height: 1.25;
}

.offering-list {
  margin: 0.85rem 0 0;
  padding-left: 1.1rem;
  color: var(--text-dim);
}

.offering-list li {
  margin-top: 0.45rem;
}

.offering-list a {
  color: var(--accent-2);
}

.offering-list a:hover {
  color: var(--text);
}

.yale-department-grid,
.mit-topic-grid {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.yale-course-list {
  list-style: none;
  padding-left: 0;
}

.yale-course-list li {
  margin-top: 0.7rem;
}

.yale-course-list a {
  display: block;
}

.yale-course-list strong {
  font-family: var(--mono);
  font-size: 0.82rem;
  letter-spacing: 0.02em;
}

.catalog-course-meta {
  display: block;
  margin-top: 0.25rem;
  color: var(--text-dim);
  font-size: 0.82rem;
}

.catalog-details {
  margin-top: 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.02);
}

.catalog-details summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  cursor: pointer;
  list-style: none;
  padding: 0.9rem 1rem;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--text);
}

.catalog-details summary::-webkit-details-marker {
  display: none;
}

.catalog-details summary::after {
  content: "+";
  color: var(--accent-2);
  font-family: var(--mono);
  font-size: 1rem;
}

.catalog-details[open] summary::after {
  content: "-";
}

.catalog-details > div {
  padding: 0 1rem 1rem;
}

.catalog-details .offerings-grid {
  margin-top: 0;
}

@media (max-width: 640px) {
  .catalog-group-top {
    flex-direction: column;
    gap: 0.35rem;
  }
}

/* External-link affordance (Phase 6 of the /learn/ course-mirror work).
   fcc-external-links.js sets target="_blank" on every outbound link; this
   marks those inside catalogue rows and descriptive copy with a small ↗
   so a visitor can tell an off-site link from an on-site mirror page
   before clicking. Chrome, buttons, and footer links are left unmarked. */
.offering-list a[target="_blank"]::after,
.section-copy a[target="_blank"]::after {
  content: " \2197";
  font-size: 0.85em;
  opacity: 0.6;
  white-space: nowrap;
}