body { background:#fbf9f4; color:#1b1c19; }
.grammar-page-shell {
  min-height: 100vh;
  max-width: var(--lesson-page-width, 1540px);
  margin: 0 auto;
}
.grammar-shell {
  display: grid;
  grid-template-columns: var(--lesson-sidebar-width, 236px) minmax(0, 1fr);
  min-height: 100vh;
}
.grammar-sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  background: #f5f3ee;
  border-right: 1px solid rgba(113, 121, 116, 0.14);
  padding: 10px 24px 24px;
  display: flex;
  flex-direction: column;
  box-sizing: border-box;
  overflow-y: auto;
}
.grammar-sidebar-brand {
  display: block;
  width: calc(100% + 34px);
  margin: -8px 0 0 -17px;
  text-decoration: none;
  line-height: 0;
  overflow: hidden;
}
.grammar-sidebar-brand .site-logo {
  display: block;
  width: calc(100% + 64px);
  max-width: none;
  height: auto;
  margin: -28px 0 -20px -32px;
}
.grammar-sidebar-nav {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-top: 34px;
  flex: 1;
}
.grammar-sidebar-link {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-left: -24px;
  padding: 14px 16px 14px 24px;
  border-radius: 0 14px 14px 0;
  color: #666761;
  text-decoration: none;
  font-size: 1.2rem;
  font-weight: 780;
  transition: background-color .18s ease, color .18s ease;
}
.grammar-sidebar-link:hover {
  background: rgba(255, 255, 255, 0.38);
  color: #1b3d2f;
}
.grammar-sidebar-link.is-active {
  background: rgba(255, 255, 255, 0.58);
  border-left: 4px solid #1b3d2f;
  color: #1b3d2f;
  padding-left: 20px;
  font-weight: 800;
}
.grammar-sidebar-start {
  margin-top: auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 14px 18px;
  border-radius: 999px;
  background: linear-gradient(135deg, #03271a 0%, #1b3d2f 100%);
  color: #fff;
  text-decoration: none;
  font-size: 1.24rem;
  font-weight: 800;
  box-sizing: border-box;
}
.grammar-main {
  padding: var(--lesson-main-padding, 40px 48px 56px);
}
.page-shell {
  max-width: var(--lesson-shell-width, 980px);
  margin: 0 auto;
  padding: var(--lesson-shell-padding, 48px 24px 72px);
  width: 100%;
  box-sizing: border-box;
  min-width: 0;
}
.page-shell section {
  background:#fff;
  border-radius: var(--lesson-section-radius, 18px);
  padding: var(--lesson-section-padding, 24px 26px);
  margin-bottom: var(--lesson-section-gap, 18px);
  box-shadow: var(--lesson-section-shadow, 0 18px 34px rgba(27,28,25,0.06));
}
.page-shell p,
.page-shell li {
  line-height: var(--lesson-copy-line-height, 1.8);
  color: var(--lesson-copy-color, #414944);
}
.page-shell ul,
.page-shell ol {
  margin-left: 18px;
}
.page-nav {
  display:flex;
  flex-wrap:wrap;
  gap:12px;
  margin:16px 0 28px;
}
.page-nav a {
  text-decoration:none;
}
.concept-grid,
.vowel-grid {
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(220px,1fr));
  gap:14px;
  margin-top:12px;
}
.concept-card,
.vowel-card {
  background:#f5f3ee;
  border-radius:14px;
  padding:16px 18px;
}
.concept-card h3,
.vowel-card h3 {
  margin:0 0 10px;
  color:#023820;
  font-size:1.05rem;
}
.example {
  margin:12px 0;
  padding:12px 14px;
  background: var(--lesson-example-bg, #f8f7f2);
  border-left:4px solid var(--lesson-example-border, #735c00);
  border-radius:10px;
}
.example strong {
  color: var(--lesson-example-strong, #023820);
}
.formula {
  margin:12px 0;
  padding:14px 16px;
  background:#0f3c2c;
  color:#fff;
  border-radius:12px;
}
.formula code {
  color:#ffe088;
  font-size:1rem;
}
.table-wrap {
  overflow-x:auto;
  max-width: 100%;
}
table.harmony-table {
  width:100%;
  border-collapse:collapse;
  margin-top:12px;
}
.harmony-table th,
.harmony-table td {
  padding:12px 10px;
  border-bottom:1px solid rgba(113,121,116,0.16);
  text-align:left;
  vertical-align:top;
}
.harmony-table th {
  color:#023820;
  font-size:.92rem;
}
@media (max-width: 900px) {
  .grammar-page-shell,
  .grammar-shell,
  .grammar-main,
  .page-shell {
    max-width: 100%;
    overflow-x: hidden;
  }
  .grammar-shell {
    grid-template-columns: 1fr;
  }
  .grammar-sidebar {
    display: none;
  }
  .grammar-main {
    padding: 0;
  }
  .page-shell {
    padding: 32px 16px 48px;
  }
  .page-shell section {
    padding: 20px 16px;
  }
  .formula code,
  .example {
    overflow-wrap: anywhere;
  }
}