/* ══════════════════════════════════════════════════════════════════
   VALMO DEVELOPMENT HANDBOOK — style.css
   Premium dark documentation UI
   ══════════════════════════════════════════════════════════════════ */

/* ── FONTS ───────────────────────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500&display=swap');

/* ── CSS CUSTOM PROPERTIES ───────────────────────────────────────── */
:root {
  /* Brand */
  --c-primary:        #6C3BFF;
  --c-primary-glow:   rgba(108, 59, 255, 0.18);
  --c-accent:         #A76DFF;
  --c-accent-subtle:  rgba(167, 109, 255, 0.1);

  /* Backgrounds */
  --c-bg:             #111111;
  --c-panel:          #1B1B1B;
  --c-card:           #222222;
  --c-card-hover:     #272727;
  --c-input:          #1E1E1E;

  /* Borders */
  --c-border:         #2F2F2F;
  --c-border-subtle:  #242424;

  /* Text */
  --c-text:           #F2F2F2;
  --c-text-secondary: #BDBDBD;
  --c-text-muted:     #707070;
  --c-text-disabled:  #3D3D3D;

  /* Semantic */
  --c-success:        #34D399;
  --c-success-bg:     rgba(52, 211, 153, 0.1);
  --c-warning:        #FBBF24;
  --c-warning-bg:     rgba(251, 191, 36, 0.1);
  --c-danger:         #EF4444;
  --c-danger-bg:      rgba(239, 68, 68, 0.1);
  --c-info:           #60A5FA;
  --c-info-bg:        rgba(96, 165, 250, 0.1);
  --c-tip:            #34D399;
  --c-tip-bg:         rgba(52, 211, 153, 0.08);
  --c-arch:           #A76DFF;
  --c-arch-bg:        rgba(167, 109, 255, 0.1);

  /* Spacing */
  --sidebar-width:    280px;
  --toc-width:        240px;
  --topbar-height:    56px;

  /* Typography */
  --font-sans:        'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono:        'JetBrains Mono', 'Fira Code', monospace;

  /* Radii */
  --r-sm:   4px;
  --r-md:   8px;
  --r-lg:   12px;
  --r-xl:   16px;
  --r-full: 9999px;

  /* Shadows */
  --shadow-sm:  0 1px 3px rgba(0,0,0,0.4);
  --shadow-md:  0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg:  0 8px 32px rgba(0,0,0,0.6);
  --shadow-purple: 0 0 24px rgba(108, 59, 255, 0.25);

  /* Transitions */
  --t-fast:   0.12s ease;
  --t-base:   0.2s ease;
  --t-slow:   0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

::selection {
  background: var(--c-primary-glow);
  color: var(--c-accent);
}

/* ── SCROLLBAR ───────────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #333; border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: #444; }

/* ── UTILITIES ───────────────────────────────────────────────────── */
.hidden { display: none !important; }
.accent { color: var(--c-accent); }
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); border: 0;
}

/* ══════════════════════════════════════════════════════════════════
   TOP BAR
   ══════════════════════════════════════════════════════════════════ */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--topbar-height);
  background: rgba(17, 17, 17, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--c-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  z-index: 100;
}

.topbar-left {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.topbar-right {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

/* Sidebar toggle */
.sidebar-toggle {
  width: 36px; height: 36px;
  background: transparent;
  border: none;
  color: var(--c-text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--r-md);
  transition: background var(--t-fast), color var(--t-fast);
  flex-shrink: 0;
}
.sidebar-toggle svg { width: 18px; height: 18px; }
.sidebar-toggle:hover { background: var(--c-card); color: var(--c-text); }

/* Topbar logo */
.topbar-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  text-decoration: none;
  flex-shrink: 0;
}
.logo-mark {
  width: 28px; height: 28px;
  background: var(--c-primary);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 14px;
  color: white;
  letter-spacing: -0.5px;
}
.logo-wordmark {
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.08em;
  color: var(--c-text);
}

.topbar-divider {
  width: 1px;
  height: 20px;
  background: var(--c-border);
  flex-shrink: 0;
}

.topbar-chapter-label {
  font-size: 13px;
  color: var(--c-text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Topbar buttons */
.topbar-btn {
  width: 36px; height: 36px;
  background: transparent;
  border: 1px solid var(--c-border);
  color: var(--c-text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--r-md);
  transition: all var(--t-fast);
}
.topbar-btn svg { width: 16px; height: 16px; }
.topbar-btn:hover {
  background: var(--c-card);
  color: var(--c-text);
  border-color: #404040;
}

/* Progress chip */
.progress-chip {
  position: relative;
  height: 28px;
  min-width: 64px;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-full);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}
.progress-chip-bar {
  position: absolute;
  left: 0; top: 0; bottom: 0;
  background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
  border-radius: var(--r-full);
  transition: width 0.5s ease;
  opacity: 0.35;
}
.progress-chip-label {
  position: relative;
  font-size: 11px;
  font-weight: 600;
  color: var(--c-text);
  padding: 0 10px;
  z-index: 1;
}

/* Reading progress bar */
.reading-progress-bar {
  position: fixed;
  top: var(--topbar-height);
  left: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
  width: 0%;
  z-index: 99;
  transition: width 0.1s linear;
}

/* ══════════════════════════════════════════════════════════════════
   LAYOUT
   ══════════════════════════════════════════════════════════════════ */
.layout {
  display: flex;
  min-height: 100vh;
  padding-top: var(--topbar-height);
}

/* ══════════════════════════════════════════════════════════════════
   LEFT SIDEBAR
   ══════════════════════════════════════════════════════════════════ */
.sidebar {
  width: var(--sidebar-width);
  background: var(--c-panel);
  border-right: 1px solid var(--c-border);
  position: fixed;
  top: var(--topbar-height);
  left: 0;
  bottom: 0;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform var(--t-slow), width var(--t-slow);
  z-index: 90;
}

.sidebar.collapsed {
  transform: translateX(-100%);
}

.sidebar-inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow-y: auto;
  overflow-x: hidden;
  padding-bottom: 16px;
}

/* Sidebar brand */
.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 20px 16px 16px;
  cursor: pointer;
  flex-shrink: 0;
}
.sidebar-logo-mark {
  width: 32px; height: 32px;
  background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 16px;
  color: white;
  flex-shrink: 0;
  box-shadow: var(--shadow-purple);
}
.sidebar-brand-text {
  display: flex;
  flex-direction: column;
  gap: 1px;
}
.sidebar-title {
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--c-text);
}
.sidebar-subtitle {
  font-size: 10px;
  color: var(--c-text-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* Sidebar search */
.sidebar-search-wrap {
  padding: 0 12px 12px;
  flex-shrink: 0;
}
.sidebar-search {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--c-input);
  border: 1px solid var(--c-border);
  border-radius: var(--r-md);
  padding: 8px 10px;
  cursor: pointer;
  transition: border-color var(--t-fast);
}
.sidebar-search:hover { border-color: #404040; }
.sidebar-search svg {
  width: 14px; height: 14px;
  color: var(--c-text-muted);
  flex-shrink: 0;
}
.sidebar-search span {
  flex: 1;
  font-size: 12px;
  color: var(--c-text-muted);
}
.sidebar-search kbd {
  font-family: var(--font-sans);
  font-size: 10px;
  color: var(--c-text-disabled);
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: 4px;
  padding: 1px 5px;
}

/* Sidebar nav */
.sidebar-nav {
  flex: 1;
  padding: 0 8px;
}

.nav-part-label {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-disabled);
  padding: 12px 8px 6px;
}

.nav-chapter-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 10px;
  border-radius: var(--r-md);
  cursor: pointer;
  transition: background var(--t-fast), color var(--t-fast);
  text-decoration: none;
  position: relative;
}
.nav-chapter-link:hover {
  background: var(--c-card);
}
.nav-chapter-link.active {
  background: var(--c-primary-glow);
  border: 1px solid rgba(108, 59, 255, 0.3);
}
.nav-chapter-link.active .nav-chapter-num {
  color: var(--c-accent);
}
.nav-chapter-link.active .nav-chapter-title {
  color: var(--c-text);
}

.nav-chapter-status {
  width: 16px; height: 16px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
}
.status-not-started { color: var(--c-text-disabled); }
.status-in-progress { color: var(--c-warning); }
.status-complete    { color: var(--c-success); }

.nav-chapter-text {
  display: flex;
  flex-direction: column;
  gap: 1px;
  min-width: 0;
}
.nav-chapter-num {
  font-size: 9px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--c-text-muted);
}
.nav-chapter-title {
  font-size: 12.5px;
  font-weight: 500;
  color: var(--c-text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Sidebar footer */
.sidebar-footer {
  padding: 12px 16px;
  border-top: 1px solid var(--c-border-subtle);
  flex-shrink: 0;
}
.sidebar-footer-info {
  display: flex;
  align-items: center;
  gap: 8px;
}
.version-badge {
  font-size: 10px;
  font-weight: 600;
  background: var(--c-primary-glow);
  color: var(--c-accent);
  border: 1px solid rgba(108, 59, 255, 0.3);
  border-radius: var(--r-full);
  padding: 2px 8px;
}
.sidebar-footer-text {
  font-size: 11px;
  color: var(--c-text-muted);
}

/* ══════════════════════════════════════════════════════════════════
   MAIN CONTENT
   ══════════════════════════════════════════════════════════════════ */
.main {
  flex: 1;
  margin-left: var(--sidebar-width);
  margin-right: var(--toc-width);
  min-width: 0;
  transition: margin var(--t-slow);
}

.main.sidebar-hidden {
  margin-left: 0;
}
.main.toc-hidden {
  margin-right: 0;
}

.page {
  min-height: calc(100vh - var(--topbar-height));
  padding: 48px 56px;
  max-width: 900px;
  margin: 0 auto;
}

/* ══════════════════════════════════════════════════════════════════
   HOME PAGE — DASHBOARD
   ══════════════════════════════════════════════════════════════════ */
.home-hero {
  margin-bottom: 48px;
}

.home-hero-eyebrow {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--c-primary);
  margin-bottom: 16px;
}

.home-hero-title {
  font-size: clamp(36px, 5vw, 52px);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--c-text);
  margin-bottom: 16px;
}

.home-hero-desc {
  font-size: 16px;
  line-height: 1.7;
  color: var(--c-text-secondary);
  max-width: 560px;
  margin-bottom: 24px;
}

.home-hero-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.meta-badge {
  font-size: 11px;
  font-weight: 500;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-full);
  padding: 4px 12px;
  color: var(--c-text-secondary);
}
.meta-badge--active {
  color: var(--c-success);
  border-color: rgba(52, 211, 153, 0.3);
  background: rgba(52, 211, 153, 0.08);
}

/* Stats row */
.stats-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
  margin-bottom: 48px;
}

.stat-card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-lg);
  padding: 20px;
  transition: border-color var(--t-base), background var(--t-base);
}
.stat-card:hover {
  border-color: #404040;
  background: var(--c-card-hover);
}

.stat-card-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-text-muted);
  margin-bottom: 10px;
}
.stat-card-value {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--c-text);
  margin-bottom: 4px;
}
.stat-card-value .stat-unit {
  font-size: 14px;
  font-weight: 400;
  color: var(--c-text-secondary);
}
.stat-card-sub {
  font-size: 11px;
  color: var(--c-text-muted);
}

.stat-card--primary .stat-card-value { color: var(--c-accent); }
.stat-card--success .stat-card-value { color: var(--c-success); }
.stat-card--warning .stat-card-value { color: var(--c-warning); }

/* Progress bar within stat card */
.stat-progress {
  margin-top: 12px;
  height: 3px;
  background: var(--c-border);
  border-radius: var(--r-full);
  overflow: hidden;
}
.stat-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--c-primary), var(--c-accent));
  border-radius: var(--r-full);
  transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Chapter grid */
.home-section {
  margin-bottom: 40px;
}
.home-section-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-muted);
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--c-border-subtle);
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 12px;
}

.chapter-card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-lg);
  padding: 20px;
  cursor: pointer;
  transition: all var(--t-base);
  position: relative;
  overflow: hidden;
}
.chapter-card::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  background: var(--c-border);
  transition: background var(--t-base);
}
.chapter-card:hover {
  border-color: #404040;
  background: var(--c-card-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}
.chapter-card:hover::before {
  background: var(--c-primary);
}
.chapter-card.status-complete::before { background: var(--c-success); }
.chapter-card.status-in-progress::before { background: var(--c-warning); }

.chapter-card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
}
.chapter-card-num {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-muted);
}
.chapter-card-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--c-text);
  line-height: 1.4;
  margin-bottom: 8px;
}
.chapter-card-desc {
  font-size: 12px;
  color: var(--c-text-secondary);
  line-height: 1.5;
}

.chapter-status-pill {
  font-size: 9px;
  font-weight: 600;
  border-radius: var(--r-full);
  padding: 3px 8px;
  white-space: nowrap;
  letter-spacing: 0.04em;
  flex-shrink: 0;
}
.pill-not-started {
  background: var(--c-card);
  color: var(--c-text-muted);
  border: 1px solid var(--c-border);
}
.pill-in-progress {
  background: var(--c-warning-bg);
  color: var(--c-warning);
  border: 1px solid rgba(251, 191, 36, 0.3);
}
.pill-complete {
  background: var(--c-success-bg);
  color: var(--c-success);
  border: 1px solid rgba(52, 211, 153, 0.3);
}

/* ══════════════════════════════════════════════════════════════════
   CHAPTER PAGE
   ══════════════════════════════════════════════════════════════════ */
.chapter-page-inner {
  max-width: 100%;
}

/* Chapter header */
.chapter-header {
  margin-bottom: 40px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--c-border-subtle);
}

.chapter-eyebrow {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
}
.chapter-num-tag {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-primary);
  background: var(--c-primary-glow);
  border: 1px solid rgba(108, 59, 255, 0.25);
  border-radius: var(--r-full);
  padding: 3px 10px;
}

.chapter-title {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
  color: var(--c-text);
  margin-bottom: 20px;
}

.chapter-meta-row {
  display: flex;
  align-items: center;
  gap: 0;
  flex-wrap: wrap;
  margin-bottom: 20px;
}
.chapter-meta-item {
  display: flex;
  align-items: center;
  gap: 5px;
  font-size: 11px;
  color: var(--c-text-muted);
  padding: 0 12px;
  border-right: 1px solid var(--c-border);
}
.chapter-meta-item:first-child { padding-left: 0; }
.chapter-meta-item:last-child { border-right: none; }
.chapter-meta-item svg { width: 12px; height: 12px; }
.chapter-meta-value { color: var(--c-text-secondary); font-weight: 500; }

/* Status selector in chapter header */
.chapter-status-control {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
}
.chapter-status-label {
  font-size: 11px;
  color: var(--c-text-muted);
  font-weight: 500;
}
.status-btn-group {
  display: flex;
  border: 1px solid var(--c-border);
  border-radius: var(--r-md);
  overflow: hidden;
}
.status-btn {
  padding: 5px 12px;
  font-size: 11px;
  font-weight: 500;
  font-family: var(--font-sans);
  background: transparent;
  border: none;
  color: var(--c-text-muted);
  cursor: pointer;
  transition: all var(--t-fast);
  border-right: 1px solid var(--c-border);
}
.status-btn:last-child { border-right: none; }
.status-btn:hover { background: var(--c-card); color: var(--c-text); }
.status-btn.active-not-started { background: var(--c-card); color: var(--c-text-secondary); }
.status-btn.active-in-progress { background: var(--c-warning-bg); color: var(--c-warning); }
.status-btn.active-complete    { background: var(--c-success-bg); color: var(--c-success); }

/* ── CHAPTER BODY TYPOGRAPHY ─────────────────────────────────────── */
.chapter-body {
  font-size: 15px;
  line-height: 1.75;
  color: var(--c-text-secondary);
}

.chapter-body h1 {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--c-text);
  margin: 40px 0 16px;
  padding-top: 8px;
}
.chapter-body h1:first-child { margin-top: 0; }

.chapter-body h2 {
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--c-text);
  margin: 32px 0 12px;
  padding-top: 4px;
}

.chapter-body h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--c-text);
  margin: 24px 0 10px;
}

.chapter-body h4 {
  font-size: 14px;
  font-weight: 600;
  color: var(--c-text-secondary);
  margin: 20px 0 8px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.chapter-body p {
  margin-bottom: 16px;
  color: var(--c-text-secondary);
}

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

.chapter-body em {
  color: var(--c-accent);
  font-style: italic;
}

.chapter-body a {
  color: var(--c-accent);
  text-decoration: none;
  border-bottom: 1px solid rgba(167, 109, 255, 0.3);
  transition: border-color var(--t-fast);
}
.chapter-body a:hover { border-color: var(--c-accent); }

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

/* Blockquote */
.chapter-body blockquote {
  border-left: 3px solid var(--c-primary);
  background: var(--c-primary-glow);
  border-radius: 0 var(--r-md) var(--r-md) 0;
  padding: 16px 20px;
  margin: 24px 0;
  font-style: italic;
  color: var(--c-text-secondary);
}
.chapter-body blockquote p { margin-bottom: 0; }

/* Inline code */
.chapter-body code {
  font-family: var(--font-mono);
  font-size: 13px;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: 4px;
  padding: 1px 6px;
  color: var(--c-accent);
}

/* Lists */
.chapter-body ul,
.chapter-body ol {
  margin: 12px 0 16px 20px;
}
.chapter-body li {
  margin-bottom: 6px;
  color: var(--c-text-secondary);
}
.chapter-body ul li { list-style-type: disc; }
.chapter-body ul li::marker { color: var(--c-primary); }
.chapter-body ol li { list-style-type: decimal; }
.chapter-body ol li::marker { color: var(--c-text-muted); }

/* ── CODE BLOCKS ──────────────────────────────────────────────────── */
.code-block-wrap {
  margin: 20px 0;
  border-radius: var(--r-lg);
  border: 1px solid var(--c-border);
  overflow: hidden;
  background: #141414;
}
.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 14px;
  background: var(--c-card);
  border-bottom: 1px solid var(--c-border);
}
.code-block-lang {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-text-muted);
}
.code-block-copy {
  font-size: 11px;
  font-weight: 500;
  font-family: var(--font-sans);
  background: transparent;
  border: 1px solid var(--c-border);
  color: var(--c-text-muted);
  border-radius: var(--r-sm);
  padding: 3px 8px;
  cursor: pointer;
  transition: all var(--t-fast);
  display: flex;
  align-items: center;
  gap: 4px;
}
.code-block-copy:hover {
  background: var(--c-input);
  color: var(--c-text);
  border-color: #404040;
}
.code-block-copy.copied {
  color: var(--c-success);
  border-color: rgba(52, 211, 153, 0.4);
  background: var(--c-success-bg);
}
.code-block-body {
  overflow-x: auto;
  padding: 16px 0;
}
.code-block-body pre {
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.7;
  color: #D4D4D4;
  padding: 0 16px;
}
.code-line {
  display: flex;
  gap: 16px;
}
.code-line-num {
  color: #404040;
  user-select: none;
  min-width: 24px;
  text-align: right;
  flex-shrink: 0;
}

/* ── TABLES ───────────────────────────────────────────────────────── */
.table-wrap {
  overflow-x: auto;
  margin: 20px 0;
  border-radius: var(--r-lg);
  border: 1px solid var(--c-border);
}
.chapter-body table,
.table-wrap table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13.5px;
}
.chapter-body th,
.table-wrap th {
  text-align: left;
  padding: 10px 14px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-text-muted);
  background: var(--c-card);
  border-bottom: 1px solid var(--c-border);
}
.chapter-body td,
.table-wrap td {
  padding: 10px 14px;
  color: var(--c-text-secondary);
  border-bottom: 1px solid var(--c-border-subtle);
}
.chapter-body tr:last-child td,
.table-wrap tr:last-child td { border-bottom: none; }
.chapter-body tr:nth-child(even) td,
.table-wrap tr:nth-child(even) td {
  background: rgba(255,255,255,0.015);
}
.chapter-body tbody tr:hover td,
.table-wrap tbody tr:hover td {
  background: var(--c-card);
}

/* ── CALLOUT BOXES ───────────────────────────────────────────────── */
.callout {
  display: flex;
  gap: 12px;
  border-radius: var(--r-lg);
  padding: 16px;
  margin: 20px 0;
  border: 1px solid;
}
.callout-icon {
  font-size: 18px;
  line-height: 1;
  flex-shrink: 0;
  margin-top: 1px;
}
.callout-content { flex: 1; min-width: 0; }
.callout-title {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 6px;
}
.callout-body { font-size: 13.5px; line-height: 1.6; }
.callout-body p { margin-bottom: 0; }
.callout-body p + p { margin-top: 8px; }

.callout-info      { background: var(--c-info-bg);    border-color: rgba(96,165,250,0.25); }
.callout-info      .callout-title { color: var(--c-info); }
.callout-tip       { background: var(--c-tip-bg);     border-color: rgba(52,211,153,0.25); }
.callout-tip       .callout-title { color: var(--c-tip); }
.callout-warning   { background: var(--c-warning-bg); border-color: rgba(251,191,36,0.25); }
.callout-warning   .callout-title { color: var(--c-warning); }
.callout-important { background: var(--c-danger-bg);  border-color: rgba(239,68,68,0.25); }
.callout-important .callout-title { color: var(--c-danger); }
.callout-arch      { background: var(--c-arch-bg);    border-color: rgba(167,109,255,0.25); }
.callout-arch      .callout-title { color: var(--c-arch); }
.callout-best      { background: var(--c-success-bg); border-color: rgba(52,211,153,0.25); }
.callout-best      .callout-title { color: var(--c-success); }
.callout-example   { background: var(--c-card);       border-color: var(--c-border); }
.callout-example   .callout-title { color: var(--c-text-secondary); }

/* ── CHECKLISTS ──────────────────────────────────────────────────── */
.checklist {
  list-style: none;
  margin: 12px 0 20px;
  padding: 0;
}
.checklist-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 6px 0;
  border-bottom: 1px solid var(--c-border-subtle);
}
.checklist-item:last-child { border-bottom: none; }
.checklist-checkbox {
  width: 16px; height: 16px;
  border: 1.5px solid var(--c-border);
  border-radius: 4px;
  background: transparent;
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  flex-shrink: 0;
  margin-top: 2px;
  transition: all var(--t-fast);
  position: relative;
}
.checklist-checkbox:hover {
  border-color: var(--c-primary);
  background: var(--c-primary-glow);
}
.checklist-checkbox:checked {
  background: var(--c-primary);
  border-color: var(--c-primary);
}
.checklist-checkbox:checked::after {
  content: '';
  position: absolute;
  left: 3px; top: 1px;
  width: 6px; height: 9px;
  border: 2px solid white;
  border-top: none;
  border-left: none;
  transform: rotate(45deg);
}
.checklist-label {
  font-size: 14px;
  color: var(--c-text-secondary);
  cursor: pointer;
  transition: color var(--t-fast);
  line-height: 1.5;
}
.checklist-checkbox:checked + .checklist-label {
  color: var(--c-text-muted);
  text-decoration: line-through;
}

/* ── REVISION HISTORY ─────────────────────────────────────────────── */
.revision-section {
  margin-top: 40px;
  padding-top: 32px;
  border-top: 1px solid var(--c-border-subtle);
}
.revision-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-muted);
  margin-bottom: 16px;
}

/* ── RELATED CHAPTERS ────────────────────────────────────────────── */
.related-section {
  margin-top: 32px;
}
.related-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-muted);
  margin-bottom: 12px;
}
.related-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.related-link {
  font-size: 12px;
  font-weight: 500;
  color: var(--c-accent);
  background: var(--c-accent-subtle);
  border: 1px solid rgba(167, 109, 255, 0.25);
  border-radius: var(--r-full);
  padding: 4px 12px;
  cursor: pointer;
  transition: all var(--t-fast);
}
.related-link:hover {
  background: rgba(167, 109, 255, 0.2);
  border-color: rgba(167, 109, 255, 0.5);
}

/* ── CHAPTER NAV ─────────────────────────────────────────────────── */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid var(--c-border-subtle);
}

.chapter-nav-btn {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-lg);
  padding: 14px 18px;
  cursor: pointer;
  transition: all var(--t-base);
  flex: 1;
  max-width: 260px;
  text-decoration: none;
}
.chapter-nav-btn:hover {
  border-color: var(--c-primary);
  background: var(--c-card-hover);
  box-shadow: 0 0 0 1px rgba(108,59,255,0.2);
}
.chapter-nav-btn.next {
  justify-content: flex-end;
  text-align: right;
  margin-left: auto;
}
.chapter-nav-btn svg {
  width: 18px; height: 18px;
  color: var(--c-text-muted);
  flex-shrink: 0;
}
.chapter-nav-text { display: flex; flex-direction: column; gap: 2px; }
.chapter-nav-direction {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-muted);
}
.chapter-nav-name {
  font-size: 13px;
  font-weight: 600;
  color: var(--c-text);
}

/* ══════════════════════════════════════════════════════════════════
   RIGHT TOC SIDEBAR
   ══════════════════════════════════════════════════════════════════ */
.toc-sidebar {
  width: var(--toc-width);
  position: fixed;
  top: var(--topbar-height);
  right: 0;
  bottom: 0;
  overflow-y: auto;
  padding: 32px 16px;
  border-left: 1px solid var(--c-border);
  background: var(--c-panel);
}

.toc-inner {
  position: sticky;
  top: 0;
}

.toc-heading {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-text-disabled);
  margin-bottom: 12px;
}

.toc-list {
  list-style: none;
}

.toc-item {
  padding: 3px 0;
}

.toc-link {
  display: block;
  font-size: 12px;
  color: var(--c-text-muted);
  text-decoration: none;
  padding: 4px 8px;
  border-left: 2px solid transparent;
  border-radius: 0 var(--r-sm) var(--r-sm) 0;
  transition: all var(--t-fast);
  line-height: 1.4;
}
.toc-link:hover {
  color: var(--c-text-secondary);
  border-left-color: var(--c-border);
}
.toc-link.active {
  color: var(--c-accent);
  border-left-color: var(--c-primary);
  background: var(--c-primary-glow);
}

.toc-link.toc-h1 { font-weight: 600; padding-left: 8px; }
.toc-link.toc-h2 { padding-left: 16px; }
.toc-link.toc-h3 { padding-left: 24px; font-size: 11.5px; }

/* ══════════════════════════════════════════════════════════════════
   SEARCH OVERLAY
   ══════════════════════════════════════════════════════════════════ */
.search-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: 200;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding-top: 80px;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-base);
}
.search-overlay.open {
  opacity: 1;
  pointer-events: all;
}

.search-modal {
  background: var(--c-panel);
  border: 1px solid var(--c-border);
  border-radius: var(--r-xl);
  width: 100%;
  max-width: 600px;
  margin: 0 16px;
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  transform: translateY(-8px);
  transition: transform var(--t-base);
}
.search-overlay.open .search-modal {
  transform: translateY(0);
}

.search-input-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  border-bottom: 1px solid var(--c-border);
}
.search-icon {
  width: 18px; height: 18px;
  color: var(--c-text-muted);
  flex-shrink: 0;
}
.search-input {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  font-family: var(--font-sans);
  font-size: 15px;
  color: var(--c-text);
}
.search-input::placeholder { color: var(--c-text-muted); }
.search-close {
  font-family: var(--font-sans);
  font-size: 10px;
  font-weight: 600;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  color: var(--c-text-muted);
  border-radius: var(--r-sm);
  padding: 3px 7px;
  cursor: pointer;
  letter-spacing: 0.04em;
}

.search-results {
  max-height: 480px;
  overflow-y: auto;
  padding: 8px;
}

.search-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 40px 20px;
  color: var(--c-text-muted);
}
.search-placeholder svg {
  width: 32px; height: 32px;
  opacity: 0.3;
}
.search-placeholder p {
  font-size: 13px;
}

.search-result-group-label {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-text-disabled);
  padding: 8px 8px 4px;
}

.search-result-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px;
  border-radius: var(--r-md);
  cursor: pointer;
  transition: background var(--t-fast);
}
.search-result-item:hover,
.search-result-item.focused {
  background: var(--c-card);
}
.search-result-icon {
  width: 28px; height: 28px;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  color: var(--c-text-muted);
  flex-shrink: 0;
}
.search-result-content { flex: 1; min-width: 0; }
.search-result-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--c-text);
  margin-bottom: 2px;
}
.search-result-title mark {
  background: var(--c-primary-glow);
  color: var(--c-accent);
  border-radius: 2px;
}
.search-result-context {
  font-size: 11px;
  color: var(--c-text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.search-result-context mark {
  background: transparent;
  color: var(--c-text-secondary);
  font-weight: 500;
}

.search-no-results {
  padding: 32px 20px;
  text-align: center;
  font-size: 13px;
  color: var(--c-text-muted);
}

/* ══════════════════════════════════════════════════════════════════
   ANIMATIONS
   ══════════════════════════════════════════════════════════════════ */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes fadeInFast {
  from { opacity: 0; }
  to   { opacity: 1; }
}
@keyframes slideInLeft {
  from { opacity: 0; transform: translateX(-12px); }
  to   { opacity: 1; transform: translateX(0); }
}

.page-enter {
  animation: fadeIn 0.25s ease forwards;
}

/* ══════════════════════════════════════════════════════════════════
   RESPONSIVE
   ══════════════════════════════════════════════════════════════════ */
@media (max-width: 1200px) {
  .toc-sidebar { display: none; }
  .main { margin-right: 0; }
}

@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
    z-index: 150;
  }
  .sidebar.mobile-open {
    transform: translateX(0);
  }
  .main {
    margin-left: 0;
    margin-right: 0;
  }
  .page { padding: 24px 20px; }
  .logo-wordmark { display: none; }
  .topbar-chapter-label { display: none; }
}

/* ══════════════════════════════════════════════════════════════════
   LAYER DIAGRAM STYLES (for architecture chapter)
   ══════════════════════════════════════════════════════════════════ */
.layer-diagram {
  margin: 20px 0;
  border: 1px solid var(--c-border);
  border-radius: var(--r-lg);
  overflow: hidden;
}
.layer-item {
  padding: 12px 20px;
  border-bottom: 1px solid var(--c-border);
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 13px;
  font-weight: 500;
  color: var(--c-text-secondary);
  transition: background var(--t-fast);
}
.layer-item:last-child { border-bottom: none; }
.layer-item:hover { background: var(--c-card); }
.layer-item:nth-child(1) { color: var(--c-accent); }
.layer-item:nth-child(2) { color: var(--c-warning); }
.layer-item:nth-child(3) { color: var(--c-success); }
.layer-item:nth-child(4) { color: var(--c-info); }
.layer-item:nth-child(5) { color: var(--c-text-muted); }
.layer-arrow {
  margin: 0;
  padding: 4px 20px;
  font-size: 16px;
  color: var(--c-text-disabled);
  background: var(--c-border-subtle);
  text-align: center;
}