:root {
  --bg: #FBF7EE;
  --surface: #FFFFFF;
  --text: #241F19;
  --text-muted: #564C3D;
  --accent: #E8A33D;
  --accent-ink: #7A4A12;
  --line: #DDCFAE;
  --level-beginner: #3D6B4C;
  --level-beginner-bg: #E2EEE3;
  --level-intermediate: #235A78;
  --level-intermediate-bg: #DFEAF0;
  --level-advanced: #8A431E;
  --level-advanced-bg: #F0E1D6;
  --radius: 12px;
  --sidebar-w: 300px;
}

html {
  font-size: calc(16px * var(--font-scale, 1));
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
}

.app {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  grid-template-rows: auto 1fr;
  min-height: 100vh;
}

.topbar {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--line);
  background: var(--surface);
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--line);
  border-radius: 8px;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  color: var(--text);
  cursor: pointer;
  flex: none;
}

.topbar-title {
  font-weight: 700;
}

.font-size-control {
  margin-left: auto;
  display: flex;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}

.font-btn {
  background: var(--bg);
  border: none;
  border-left: 1px solid var(--line);
  color: var(--text);
  font-family: inherit;
  font-weight: 700;
  cursor: pointer;
  width: 44px;
  height: 40px;
  font-size: 0.85rem;
}

.font-btn:first-child { border-left: none; }
.font-btn:hover { background: var(--surface); color: var(--accent-ink); }
#fontDec { font-size: 0.75rem; }
#fontInc { font-size: 0.95rem; }

.sidebar {
  border-right: 1px solid var(--line);
  padding: 32px 16px;
  overflow-y: auto;
}

.sidebar-title {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  padding: 0 12px 16px;
}

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

.lesson-list li a {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--text);
  text-decoration: none;
  border-left: 3px solid transparent;
}

.lesson-list li a:hover {
  background: var(--surface);
}

.lesson-list li a.active {
  background: var(--surface);
  border-left-color: var(--accent);
  font-weight: 700;
}

.lesson-num {
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  min-width: 1.6em;
}

.content {
  padding: 48px 40px;
  max-width: 760px;
}

.placeholder {
  color: var(--text-muted);
}

.lesson-header {
  margin-bottom: 32px;
}

.lesson-eyebrow {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin: 0 0 4px;
}

.lesson-title {
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.2;
  margin: 0;
}

.level-tabs {
  display: flex;
  gap: 24px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 32px;
}

.level-tab {
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: 10px 2px;
  font-size: 1rem;
  font-family: inherit;
  color: var(--text-muted);
  cursor: pointer;
}

.level-tab[data-level="beginner"].active { color: var(--level-beginner); border-color: var(--level-beginner); }
.level-tab[data-level="intermediate"].active { color: var(--level-intermediate); border-color: var(--level-intermediate); }
.level-tab[data-level="advanced"].active { color: var(--level-advanced); border-color: var(--level-advanced); }

.level-panel { display: none; }
.level-panel.active { display: block; }

.field { margin-bottom: 28px; }

.field-label {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin: 0 0 10px;
}

.level-panel[data-level="beginner"] .field-label { color: var(--level-beginner); }
.level-panel[data-level="intermediate"] .field-label { color: var(--level-intermediate); }
.level-panel[data-level="advanced"] .field-label { color: var(--level-advanced); }

.verse-block {
  border-left: 4px solid var(--accent);
  background: var(--surface);
  border-radius: 0 8px 8px 0;
  padding: 12px 16px;
  font-style: normal;
  font-weight: 400;
  color: var(--text);
}

.level-panel[data-level="beginner"] .verse-block { border-left-color: var(--level-beginner); background: var(--level-beginner-bg); }
.level-panel[data-level="intermediate"] .verse-block { border-left-color: var(--level-intermediate); background: var(--level-intermediate-bg); }
.level-panel[data-level="advanced"] .verse-block { border-left-color: var(--level-advanced); background: var(--level-advanced-bg); }

.verse-text { display: block; }

.verse-ref {
  display: block;
  margin-top: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.field-body { margin: 0; white-space: pre-line; }

.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.lesson-nav a {
  color: var(--text);
  text-decoration: none;
  padding: 10px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  font-size: 0.9rem;
}

.lesson-nav a:hover { border-color: var(--accent); }

@media (max-width: 860px) {
  .app { grid-template-columns: 1fr; }
  .nav-toggle { display: flex; }
  .sidebar {
    position: fixed;
    top: var(--topbar-h, 69px);
    left: 0;
    bottom: 0;
    width: min(85vw, 320px);
    background: var(--bg);
    transform: translateX(-100%);
    transition: transform 0.2s ease;
    z-index: 10;
  }
  .sidebar.open { transform: translateX(0); box-shadow: 0 0 0 2000px rgba(0,0,0,0.15); }
  .content { padding: 24px 20px 60px; }
  .lesson-title { font-size: 1.5rem; }
  .level-tabs { gap: 16px; }
  .level-tab { padding: 12px 4px; font-size: 0.95rem; }
  .lesson-nav { flex-direction: column; }
  .lesson-nav a { text-align: center; padding: 14px 16px; }
}

@media (max-width: 420px) {
  .topbar-title { display: none; }
  .font-size-control { margin-left: 0; }
}