/* ── Custom Properties ─────────────────────────────────────────────────── */
:root {
  --bg:           #090909;
  --surface:      #101010;
  --surface-2:    #171717;
  --surface-3:    #1e1e1e;
  --border:       #222;
  --border-hover: #333;
  --text:         #e8e8e8;
  --text-muted:   #6b6b6b;
  --text-faint:   #333;
  --accent:       #818cf8;
  --accent-glow:  rgba(129, 140, 248, 0.15);
  --green:        #34d399;
  --green-dim:    rgba(52, 211, 153, 0.12);
  --amber:        #fbbf24;
  --amber-dim:    rgba(251, 191, 36, 0.12);
  --planned:      #374151;
  --planned-dim:  rgba(55, 65, 81, 0.3);

  --font:         system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono:    "SF Mono", ui-monospace, "Cascadia Code", "Roboto Mono", monospace;

  --radius:       8px;
  --radius-lg:    12px;
  --nav-h:        60px;
  --sidebar-w:    260px;
  --content-max:  760px;
}

/* ── Light Theme ──────────────────────────────────────────────────────── */
[data-theme="light"] {
  --bg:           #f0ece3;
  --surface:      #e6e1d6;
  --surface-2:    #dbd5c8;
  --surface-3:    #cfc8b9;
  --border:       #cac3b2;
  --border-hover: #b0a896;
  --text:         #0f0f0f;
  --text-muted:   #595959;
  --text-faint:   #d0d0d0;
  --accent:       #4f46e5;
  --accent-glow:  rgba(79, 70, 229, 0.08);
  --green:        #059669;
  --green-dim:    rgba(5, 150, 105, 0.08);
  --amber:        #d97706;
  --amber-dim:    rgba(217, 119, 6, 0.08);
  --planned:      #9ca3af;
  --planned-dim:  rgba(156, 163, 175, 0.12);
}

[data-theme="light"] #nav {
  background: rgba(240, 236, 227, 0.92);
}

[data-theme="light"] .hero h1 em {
  background: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
  -webkit-background-clip: text;
  background-clip: text;
}

/* Mermaid wrap stays dark in both themes — diagrams look correct on dark bg */
[data-theme="light"] .mermaid-wrap {
  background: #1a1a2e;
  border-color: #2e2e4a;
}

/* ── Reset ─────────────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

a { color: inherit; text-decoration: none; }

img, svg { display: block; max-width: 100%; }

/* ── Nav ────────────────────────────────────────────────────────────────── */
#nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(9, 9, 9, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text);
  transition: opacity 0.15s;
}
.nav-logo:hover { opacity: 0.7; }
.logo-accent { color: var(--accent); }

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-link {
  font-size: 14px;
  color: var(--text-muted);
  transition: color 0.15s;
}
.nav-link:hover { color: var(--text); }

.nav-github {
  font-size: 13px;
  color: var(--text-muted);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 5px 12px;
  transition: all 0.15s;
}
.nav-github:hover {
  color: var(--text);
  border-color: var(--border-hover);
  background: var(--surface-2);
}

/* Theme toggle */
.theme-toggle {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 15px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s;
  flex-shrink: 0;
}
.theme-toggle:hover {
  background: var(--surface-2);
  color: var(--text);
  border-color: var(--border-hover);
}

/* ── Loading ─────────────────────────────────────────────────────────────── */
.loading {
  text-align: center;
  padding: 80px 24px;
  color: var(--text-muted);
  font-size: 14px;
}

/* ── ── ── HOME PAGE ── ── ── ────────────────────────────────────────────── */

/* Hero */
.hero {
  max-width: 1200px;
  margin: 0 auto;
  padding: 80px 24px 48px;
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--accent);
  border: 1px solid rgba(129, 140, 248, 0.25);
  border-radius: 100px;
  padding: 4px 12px;
  margin-bottom: 24px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(36px, 5vw, 60px);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 20px;
  color: var(--text);
}

.hero h1 em {
  font-style: normal;
  background: linear-gradient(135deg, var(--accent) 0%, #a5b4fc 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-sub {
  font-size: 17px;
  color: var(--text-muted);
  max-width: 580px;
  margin: 0 auto 40px;
  line-height: 1.65;
}

/* Stats bar */
.stats-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  margin: 0 auto 64px;
  max-width: 560px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
  overflow: hidden;
}

.stat {
  flex: 1;
  padding: 16px 20px;
  text-align: center;
  border-right: 1px solid var(--border);
}
.stat:last-child { border-right: none; }

.stat-value {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}

.stat-label {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* Phase grid section */
.phases-section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px 80px;
}

.section-header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 32px;
}

.section-title {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.legend {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-left: auto;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--text-muted);
}

.legend-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
}
.legend-dot.complete { background: var(--green); }
.legend-dot.progress { background: var(--amber); }
.legend-dot.planned  { background: var(--planned); }

/* Phase grid */
.phase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(272px, 1fr));
  gap: 12px;
}

/* Phase card */
.phase-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px 28px 44px;
  cursor: pointer;
  transition: border-color 0.15s, transform 0.15s, background 0.15s;
  overflow: hidden;
  text-align: left;
}

.phase-card:hover {
  border-color: var(--border-hover);
  background: var(--surface-2);
  transform: translateY(-1px);
}

.phase-card.complete {
  border-color: rgba(52, 211, 153, 0.2);
}
.phase-card.complete:hover {
  border-color: rgba(52, 211, 153, 0.4);
}

.phase-card.progress {
  border-color: rgba(251, 191, 36, 0.2);
}
.phase-card.progress:hover {
  border-color: rgba(251, 191, 36, 0.4);
}

/* Large background phase number */
.phase-card-num {
  position: absolute;
  top: 12px;
  right: 16px;
  font-size: 56px;
  font-weight: 800;
  letter-spacing: -0.04em;
  color: var(--text-faint);
  line-height: 1;
  pointer-events: none;
  user-select: none;
  font-variant-numeric: tabular-nums;
}

.phase-card-status {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 14px;
}

.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  flex-shrink: 0;
}
.status-dot.complete { background: var(--green); box-shadow: 0 0 6px var(--green); }
.status-dot.progress { background: var(--amber); box-shadow: 0 0 6px var(--amber); }
.status-dot.planned  { background: var(--planned); }

.status-label {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.status-label.complete { color: var(--green); }
.status-label.progress { color: var(--amber); }
.status-label.planned  { color: var(--text-muted); }

.phase-card-wrap {
  position: relative;
  display: flex;
  flex-direction: column;
}

.phase-card-wrap > .phase-card {
  flex: 1;
}

.slides-btn {
  position: absolute;
  bottom: 14px;
  right: 14px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--accent);
  text-decoration: none;
  border: 1px solid var(--accent);
  border-radius: 4px;
  padding: 4px 10px;
  opacity: 0.7;
  transition: opacity 0.15s, background 0.15s;
  background: transparent;
  z-index: 1;
}
.slides-btn:hover {
  opacity: 1;
  background: var(--accent-glow);
}

.phase-card-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 8px;
  line-height: 1.3;
  padding-right: 40px;
}

.phase-card-desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.5;
  margin-bottom: 20px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.phase-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.phase-card-meta {
  font-size: 12px;
  color: var(--text-muted);
}

/* Progress bar */
.phase-progress {
  margin-top: 16px;
}

.phase-progress-bar {
  height: 3px;
  background: var(--surface-3);
  border-radius: 2px;
  overflow: hidden;
}

.phase-progress-fill {
  height: 100%;
  border-radius: 2px;
  background: var(--green);
  transition: width 0.3s ease;
}
.phase-card.planned .phase-progress-fill { background: var(--planned); }
.phase-card.progress .phase-progress-fill { background: var(--amber); }

.phase-progress-text {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 6px;
}

/* ── ── ── PHASE PAGE ── ── ── ───────────────────────────────────────────── */

.phase-page {
  max-width: 900px;
  margin: 0 auto;
  padding: 40px 24px 80px;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 32px;
}
.breadcrumb a { color: var(--text-muted); transition: color 0.15s; }
.breadcrumb a:hover { color: var(--text); }
.breadcrumb-sep { color: var(--text-faint); }

.phase-header {
  margin-bottom: 40px;
}

.phase-num-badge {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.phase-header h1 {
  font-size: clamp(24px, 3.5vw, 36px);
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 12px;
  color: var(--text);
}

.phase-header-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.phase-header-meta .tag {
  font-size: 12px;
  color: var(--text-muted);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 100px;
  padding: 3px 10px;
}

.phase-desc {
  font-size: 15px;
  color: var(--text-muted);
  line-height: 1.65;
  margin: 20px 0 40px;
  max-width: 620px;
}

/* Lesson table */
.lesson-table {
  width: 100%;
  border-collapse: collapse;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.lesson-table thead tr {
  background: var(--surface-2);
}

.lesson-table th {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.lesson-table td {
  padding: 14px 16px;
  font-size: 14px;
  border-bottom: 1px solid var(--border);
  vertical-align: middle;
}

.lesson-table tr:last-child td { border-bottom: none; }

.lesson-table tr.clickable {
  cursor: pointer;
  transition: background 0.1s;
}
.lesson-table tr.clickable:hover { background: var(--surface-2); }

.lesson-table tr.planned td { opacity: 0.5; cursor: default; }
.lesson-table tr.planned:hover { background: transparent; }

.lesson-num {
  font-size: 12px;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  width: 40px;
}

.lesson-title-cell { color: var(--text); }

.lesson-time {
  font-size: 12px;
  color: var(--text-muted);
  white-space: nowrap;
  text-align: right;
}

/* Status pill */
.status-pill {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.04em;
  border-radius: 100px;
  padding: 3px 8px;
  white-space: nowrap;
}
.status-pill.complete { color: var(--green); background: var(--green-dim); }
.status-pill.progress { color: var(--amber); background: var(--amber-dim); }
.status-pill.planned  { color: var(--text-muted); background: var(--planned-dim); }

/* ── ── ── LESSON PAGE ── ── ── ──────────────────────────────────────────── */

.lesson-layout {
  display: flex;
  min-height: calc(100vh - var(--nav-h));
}

/* Sidebar */
.lesson-sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  position: sticky;
  top: var(--nav-h);
  height: calc(100vh - var(--nav-h));
  overflow-y: auto;
  border-right: 1px solid var(--border);
  padding: 24px 0;
}

.sidebar-phase-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 0 20px 12px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 8px;
}

.sidebar-lesson {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 20px;
  font-size: 13px;
  color: var(--text-muted);
  cursor: pointer;
  transition: background 0.1s, color 0.1s;
  line-height: 1.35;
}

.sidebar-lesson:hover:not(.planned) {
  background: var(--surface-2);
  color: var(--text);
}

.sidebar-lesson.active {
  background: var(--accent-glow);
  color: var(--accent);
}

.sidebar-lesson.planned {
  opacity: 0.4;
  cursor: default;
}

.sidebar-lesson-num {
  font-size: 11px;
  color: var(--text-faint);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
  width: 20px;
}

.sidebar-status {
  margin-left: auto;
  flex-shrink: 0;
}

/* Lesson content */
.lesson-content {
  flex: 1;
  min-width: 0;
  padding: 40px 48px 80px;
}

.lesson-content-inner {
  max-width: var(--content-max);
  margin: 0 auto;
}

/* Colab badge */
.colab-badge-wrap {
  margin-bottom: 16px;
}
.colab-badge-wrap img {
  height: 20px;
  border-radius: 4px;
}

/* Lesson meta header */
.lesson-meta-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border);
}

.meta-tag {
  font-size: 12px;
  color: var(--text-muted);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 3px 8px;
}
.meta-tag strong {
  color: var(--text);
  font-weight: 600;
}

/* ── ── ── MARKDOWN CONTENT ── ── ── ─────────────────────────────────────── */

.md-body {
  color: var(--text);
  line-height: 1.7;
}

.md-body h1 {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.025em;
  margin: 0 0 24px;
  color: var(--text);
}

.md-body h2 {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -0.015em;
  margin: 48px 0 16px;
  padding-top: 48px;
  border-top: 1px solid var(--border);
  color: var(--text);
}

.md-body h2:first-of-type { margin-top: 0; padding-top: 0; border-top: none; }

.md-body h3 {
  font-size: 15px;
  font-weight: 600;
  margin: 28px 0 12px;
  color: var(--text);
}

.md-body h4 {
  font-size: 14px;
  font-weight: 600;
  margin: 20px 0 8px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.md-body p {
  margin: 0 0 16px;
  color: var(--text);
}

.md-body ul, .md-body ol {
  padding-left: 20px;
  margin: 0 0 16px;
}

.md-body li {
  margin-bottom: 6px;
}

.md-body li + li { margin-top: 4px; }

.md-body strong { color: var(--text); font-weight: 600; }

.md-body em { color: var(--text-muted); }

.md-body a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: opacity 0.15s;
}
.md-body a:hover { opacity: 0.8; }

.md-body hr {
  border: none;
  border-top: 1px solid var(--border);
  margin: 32px 0;
}

/* Blockquotes — Real-world check / Perspective shift */
.md-body blockquote {
  border-left: 3px solid var(--accent);
  background: var(--accent-glow);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 16px 20px;
  margin: 24px 0;
  color: var(--text);
}

.md-body blockquote p { margin: 0; }

.md-body blockquote strong {
  color: var(--accent);
  display: block;
  margin-bottom: 6px;
  font-size: 12px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* Inline code */
.md-body code:not(pre code) {
  font-family: var(--font-mono);
  font-size: 13px;
  background: var(--surface-3);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
  color: #a5b4fc;
}
[data-theme="light"] .md-body code:not(pre code) { color: #4f46e5; }

/* Code blocks */
.code-block {
  position: relative;
  margin: 20px 0;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  overflow: hidden;
  background: var(--surface-2);
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 14px;
  background: var(--surface-3);
  border-bottom: 1px solid var(--border);
}

.code-lang {
  font-size: 11px;
  font-family: var(--font-mono);
  color: var(--text-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.copy-btn {
  font-size: 11px;
  color: var(--text-muted);
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 3px 8px;
  cursor: pointer;
  font-family: var(--font);
  transition: all 0.15s;
}

.copy-btn:hover {
  color: var(--text);
  border-color: var(--border-hover);
  background: var(--surface);
}

.copy-btn.copied {
  color: var(--green);
  border-color: rgba(52, 211, 153, 0.3);
}

.code-block pre {
  margin: 0;
  padding: 16px;
  overflow-x: auto;
  background: transparent !important;
}

.code-block code {
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.6;
  background: transparent !important;
}

/* Mermaid diagrams */
.mermaid-wrap {
  margin: 24px 0;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  overflow-x: auto;
  text-align: center;
}

.mermaid { display: inline-block; }

/* Tables */
.md-body table {
  width: 100%;
  border-collapse: collapse;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin: 20px 0;
  font-size: 14px;
}

.md-body th {
  background: var(--surface-2);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 10px 14px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.md-body td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.md-body tr:last-child td { border-bottom: none; }
.md-body tr:hover td { background: var(--surface-2); }

/* Lesson prev/next */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 56px;
  padding-top: 32px;
  border-top: 1px solid var(--border);
}

.lesson-nav-btn {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 16px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all 0.15s;
  flex: 1;
  max-width: 48%;
}

.lesson-nav-btn:hover {
  border-color: var(--border-hover);
  background: var(--surface-2);
}

.lesson-nav-btn.next { text-align: right; }

.lesson-nav-dir {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.lesson-nav-title {
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
}

/* ── ── ── 404 / NOT BUILT ── ── ── ──────────────────────────────────────── */

.not-built {
  text-align: center;
  padding: 80px 24px;
}

.not-built-icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.not-built h2 {
  font-size: 22px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 12px;
}

.not-built p {
  font-size: 15px;
  color: var(--text-muted);
  max-width: 440px;
  margin: 0 auto 32px;
  line-height: 1.6;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  font-weight: 500;
  padding: 10px 20px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
  cursor: pointer;
  transition: all 0.15s;
}

.btn:hover {
  border-color: var(--border-hover);
  background: var(--surface-2);
}

/* ── Scrollbar ───────────────────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--surface-3); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--border-hover); }

/* ── Mobile sidebar overlay ──────────────────────────────────────────────── */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  z-index: 199;
  backdrop-filter: blur(2px);
}
.sidebar-overlay.open { display: block; }

.lesson-sidebar {
  transform: translateX(0);
  transition: transform 0.25s ease;
}

/* Mobile contents toggle button */
.mobile-toc-btn {
  display: none;
  width: 100%;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-muted);
  font-size: 13px;
  font-family: var(--font);
  cursor: pointer;
  margin-bottom: 20px;
  transition: all 0.15s;
}
.mobile-toc-btn:hover {
  border-color: var(--border-hover);
  color: var(--text);
}

/* ── Code block — mobile touch scroll ───────────────────────────────────── */
.code-block pre {
  -webkit-overflow-scrolling: touch;
}

/* ── Responsive ─────────────────────────────────────────────────────────── */
@media (max-width: 900px) {
  /* Sidebar becomes a slide-in drawer on tablet/mobile */
  .lesson-sidebar {
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    z-index: 200;
    transform: translateX(-100%);
    background: var(--bg);
    border-right: 1px solid var(--border);
    padding-top: calc(var(--nav-h) + 16px);
  }

  .lesson-sidebar.open {
    transform: translateX(0);
  }

  .lesson-content { padding: 24px 20px 60px; }
  .mobile-toc-btn { display: flex; }
}

@media (max-width: 768px) {
  /* Nav */
  .nav-links .nav-link { display: none; }

  /* Hero */
  .hero { padding: 48px 16px 32px; }
  .hero h1 { letter-spacing: -0.02em; }
  .hero-sub { font-size: 15px; }

  /* Stats */
  .stats-bar { max-width: 100%; }
  .stat { padding: 14px 8px; }
  .stat-value { font-size: 20px; }
  .stat-label { font-size: 11px; }

  /* Phases */
  .phases-section { padding: 0 16px 60px; }
  .legend { display: none; }
  .phase-grid { grid-template-columns: 1fr 1fr; gap: 10px; }
  .phase-card { padding: 18px 18px 40px; }
  .phase-card-desc { display: none; }
  .phase-card-num { font-size: 40px; top: 10px; right: 12px; }

  /* Phase page */
  .phase-page { padding: 24px 16px 60px; }

  /* Lesson table — hide time column on small screens */
  .lesson-table .lesson-time { display: none; }

  /* Lesson nav */
  .lesson-nav { flex-direction: column; }
  .lesson-nav-btn { max-width: 100%; }

  /* Code blocks */
  .code-block { border-radius: var(--radius); }
  .code-block pre { padding: 12px; }
  .code-block code { font-size: 12px; }
  .code-block-header { padding: 6px 12px; }
}

@media (max-width: 480px) {
  .phase-grid { grid-template-columns: 1fr; }
  .phase-card-desc { display: -webkit-box; } /* restore on single column */

  /* lesson meta tags wrap */
  .lesson-meta-bar { gap: 6px; }
  .meta-tag { font-size: 11px; }

  /* breadcrumb truncate middle items */
  .breadcrumb span:not(:last-child):not(.breadcrumb-sep) { max-width: 100px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
}

/* Tablet — wider phase grid */
@media (min-width: 769px) and (max-width: 1024px) {
  .phase-grid { grid-template-columns: repeat(3, 1fr); }
}

/* ── ── ── RTL / Arabic ── ── ── ─────────────────────────────────────────────
   Flexbox and flow content mirror automatically under dir="rtl"; the rules
   below flip the physical (left/right) properties that do not. Code blocks and
   diagrams are forced back to LTR — code is always read left-to-right. */

/* Hero badge separators contain Latin punctuation; keep readable */
html[dir="rtl"] { text-align: right; }

/* Stat dividers */
html[dir="rtl"] .stat { border-right: none; border-left: 1px solid var(--border); }
html[dir="rtl"] .stat:last-child { border-left: none; }

/* Push legend to the inline-end */
html[dir="rtl"] .legend { margin-left: 0; margin-right: auto; }

/* Phase cards */
html[dir="rtl"] .phase-card { text-align: right; }
html[dir="rtl"] .phase-card-num { right: auto; left: 16px; }
html[dir="rtl"] .phase-card-title { padding-right: 0; padding-left: 40px; }
html[dir="rtl"] .slides-btn { right: auto; left: 14px; }

/* Tables */
html[dir="rtl"] .lesson-table th,
html[dir="rtl"] .md-body th { text-align: right; }
html[dir="rtl"] .lesson-table th[style] { text-align: left !important; }
html[dir="rtl"] .lesson-time { text-align: left; }

/* Lesson sidebar — sits on the right, divider on its inline-start */
html[dir="rtl"] .lesson-sidebar { border-right: none; border-left: 1px solid var(--border); }
html[dir="rtl"] .sidebar-status { margin-left: 0; margin-right: auto; }

/* Markdown lists + blockquotes */
html[dir="rtl"] .md-body ul,
html[dir="rtl"] .md-body ol { padding-left: 0; padding-right: 20px; }
html[dir="rtl"] .md-body blockquote {
  border-left: none;
  border-right: 3px solid var(--accent);
  border-radius: var(--radius) 0 0 var(--radius);
}

/* Prev/next: "next" sits on the inline-start under RTL */
html[dir="rtl"] .lesson-nav-btn.next { text-align: left; }

/* Code and diagrams stay LTR */
html[dir="rtl"] .code-block,
html[dir="rtl"] .code-block pre,
html[dir="rtl"] .code-block code,
html[dir="rtl"] .md-body pre,
html[dir="rtl"] .mermaid-wrap { direction: ltr; text-align: left; }

/* Mobile drawer slides in from the right under RTL */
@media (max-width: 900px) {
  html[dir="rtl"] .lesson-sidebar {
    left: auto;
    right: 0;
    transform: translateX(100%);
    border-left: none;
    border-right: 1px solid var(--border);
  }
  html[dir="rtl"] .lesson-sidebar.open { transform: translateX(0); }
}

@media (max-width: 768px) {
  html[dir="rtl"] .phase-card-num { right: auto; left: 12px; }
}

/* Footer */
.site-footer {
  text-align: center;
  padding: 1.5rem 1rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border);
  margin-top: 2rem;
}
.site-footer a { color: var(--text-muted); text-decoration: underline; }
.site-footer a:hover { color: var(--accent); }