.lesson {
  max-width: 900px;
  margin: 2rem auto;
  padding: 2rem;
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  border: 1px solid var(--border);
}

.lesson h1 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
  color: var(--primary);
}

.lesson p,
.lesson li {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text-main);
}

.lesson h2 {
  margin-top: 1.8rem;
  margin-bottom: 0.8rem;
  font-size: 1.4rem;
  color: var(--text-main);
}

.lesson h3 {
  margin-top: 1.5rem;
  margin-bottom: 0.6rem;
  font-size: 1.2rem;
  color: var(--text-muted);
}


.lesson section,
.lesson .scenario,
.lesson .practice,
.lesson .note-box {
  margin: 1.2rem 0;
  padding: 1.1rem 1.3rem;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
}


.lesson .scenario {
  border-left: 4px solid var(--primary);
}


.lesson .practice {
  border-left: 4px solid var(--secondary);
}


.lesson .page-card {
  max-width: 900px;
  margin: 2rem auto;
  padding: 2rem;
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  border: 1px solid var(--border);
}

.lesson .lesson-list {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
}

.lesson-list-item {
  margin-bottom: 1.2rem;
  padding: 0.9rem 1rem;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.lesson-list-link {
  color: var(--primary);
  text-decoration: none;
}

.lesson-list-link:hover {
  text-decoration: underline;
}

.lesson-list-meta {
  font-size: 0.9rem;
  color: #b3bac2;
  margin-top: 0.2rem;
}

.lesson-list-summary {
  margin-top: 0.4rem;
  font-size: 0.95rem;
  color: #dde2e7;
}


.lesson iframe {
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-body);
}

.reveal-card {
  margin: 1rem 0 1.5rem;
  padding: 1rem 1.25rem;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  cursor: pointer;
}

.reveal-card summary {
  list-style: none;
  font-weight: 600;
  color: var(--primary);
}

.reveal-card[open] {
  background: rgba(6, 182, 212, 0.08);
}

.reveal-card__answer {
  margin-top: 0.75rem;
  color: var(--text-muted);
}

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