.page-shell {
  max-width: var(--topic-shell-width, 980px);
  margin: 0 auto;
  padding: var(--topic-shell-padding, 44px 24px 72px);
}

.page-shell section {
  background: #fff;
  border-radius: var(--topic-section-radius, 18px);
  padding: var(--topic-section-padding, 22px 24px);
  margin-bottom: 18px;
  box-shadow: var(--topic-section-shadow, 0 16px 32px rgba(27,28,25,0.06));
}

.page-shell p,
.page-shell li {
  line-height: var(--topic-copy-line-height, 1.85);
  color: var(--topic-copy-color, #414942);
}

.page-shell ul,
.page-shell ol {
  margin-left: 18px;
}

.page-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 14px 0 24px;
}

.page-nav a {
  text-decoration: none;
}

.example {
  margin: 12px 0;
  padding: 12px 14px;
  background: var(--topic-example-bg, #f8f7f2);
  border-left: 4px solid var(--topic-example-border, #735c00);
  border-radius: 10px;
}

.example strong {
  color: var(--topic-example-strong, #023820);
}

.formula {
  margin: 12px 0;
  padding: 14px 16px;
  background: var(--topic-formula-bg, #0f3c2c);
  color: var(--topic-formula-color, #fff);
  border-radius: 12px;
}

.formula code {
  color: var(--topic-formula-accent, #ffe088);
  font-size: 1rem;
}

.table-wrap {
  overflow-x: auto;
}

.page-shell table,
.page-shell table.lesson-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 12px;
}

.page-shell th,
.page-shell td,
.page-shell .lesson-table th,
.page-shell .lesson-table td {
  border: 1px solid rgba(0,0,0,0.08);
  padding: 10px 12px;
  text-align: left;
  vertical-align: top;
}

.page-shell th,
.page-shell .lesson-table th {
  background: #f5f3ee;
  color: var(--topic-table-head-color, inherit);
}