:root {
    --navy: #071828;
    --navy-mid: #0d2236;
    --navy-light: #873cf015;
    --cyan: #883CF0;
    --cyan-dim: #883CF0;
    --cyan-glow: #23133a;
    --white: #f0f8ff;
    --muted: #d6d6d6;
    --border: #3a1c63;
    --warn: #f5a623;
    --success: #34d399;
    --card-bg: #23133a;
  }

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

  .strongdm-201-training-guide {
    
    background: var(--navy);
    color: var(--white);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
  }

  /* ── LAYOUT ── */
  .shell { display: flex; min-height: 100vh; position: relative; }

  /* ── SIDEBAR ── */
  .strongdm-201-training-guide .sidebar {
    width: 280px;
    min-height: 100vh;
    background: #180f26;
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    backdrop-filter: blur(12px);
  }

  .sidebar-brand {
    padding: 28px 24px 20px;
    border-bottom: 1px solid var(--border);
  }

  .brand-logo {
    font-size: 22px;
    font-weight: 800;
  }
  .brand-logo span { color: var(--cyan); }

  .brand-subtitle {
    font-size: 10px;
    color: var(--muted);
    margin-top: 4px;
    text-transform: uppercase;
  }

  /* Overall progress */
  .overall-progress {
    padding: 16px 24px;
    border-bottom: 1px solid var(--border);
  }
  .progress-label {
    font-size: 11px;
    color: var(--muted);
    text-transform: uppercase;
    margin-bottom: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  .progress-label strong { color: var(--cyan); }
  .progress-bar-outer {
    height: 4px;
    background: rgba(255,255,255,0.08);
    border-radius: 99px;
    overflow: hidden;
  }
  .progress-bar-inner {
    height: 100%;
    background: linear-gradient(90deg, var(--cyan-dim), var(--cyan));
    border-radius: 99px;
    transition: width 0.5s ease;
    width: 0%;
  }

  /* Nav sections */
  .nav-section-label {
    padding: 16px 24px 6px;
    font-size: 9px;
    color: var(--muted);
    text-transform: uppercase;
  }

  .nav-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 24px;
    cursor: pointer;
    font-size: 13.5px;
    font-weight: 500;
    color: var(--muted);
    border-left: 2px solid transparent;
    transition: all 0.2s;
    text-decoration: none;
  }
  .nav-item:hover { color: var(--white); background: var(--cyan-glow); }
  .nav-item.active { color: var(--cyan); border-left-color: var(--cyan); background: var(--cyan-glow); }
  .nav-item.completed { color: var(--success); }
  .nav-item.completed .nav-check { opacity: 1; }

  .nav-num {
    
    font-size: 10px;
    color: inherit;
    opacity: 0.6;
    min-width: 18px;
  }
  .nav-check {
    margin-left: auto;
    color: var(--success);
    font-size: 13px;
    opacity: 0;
    transition: opacity 0.3s;
  }

  /* ── MAIN ── */
  .main {
    flex: 1;
    padding: 48px 56px;
    /* max-width: 900px; */
    height: 100vh;
    overflow-y: scroll;
    background-color: #191127;
    position: relative;
  }

  /* Module header */
  .module-header {
    margin-bottom: 48px;
    opacity: 0;
    animation: fadeUp 0.6s ease forwards;
  }

  .module-tag {
    font-size: 10px;
    text-transform: uppercase;
    color: var(--cyan);
    margin-bottom: 10px;
  }

  .module-title {
    font-size: 42px;
    font-weight: 800;
    line-height: 1.05;
    margin-bottom: 14px;
  }

  .module-desc {
    font-size: 16px;
    color: var(--muted);
    line-height: 1.65;
    max-width: 600px;
  }

  /* Section */
  .section {
    margin-bottom: 40px;
    opacity: 0;
    animation: fadeUp 0.6s ease forwards;
  }
  .section:nth-child(2) { animation-delay: 0.1s; }
  .section:nth-child(3) { animation-delay: 0.2s; }
  .section:nth-child(4) { animation-delay: 0.3s; }
  .section:nth-child(5) { animation-delay: 0.4s; }

  .section-header {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 20px;
  }

  .section-icon {
    width: 40px; height: 40px;
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    font-size: 18px;
    flex-shrink: 0;
    background: #23133a;
    border: 1px solid var(--border);
  }

  .section-title {
    
    font-size: 22px;
    font-weight: 700;
  }

  /* Info card */
  .card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 24px 28px;
    margin-bottom: 16px;
    backdrop-filter: blur(8px);
    transition: border-color 0.2s, box-shadow 0.2s;
  }
  .card:hover { border-color: #5e309d; box-shadow: 0 4px 32px #be52e50f; }

  .card-title {
    
    font-size: 15px;
    font-weight: 700;
    color: var(--cyan);
    margin-bottom: 10px;
  }

  .card p {
    font-size: 14.5px;
    color: #c0d8ea;
    line-height: 1.7;
  }

  .bullet-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 4px;
  }
  .bullet-list li {
    display: flex;
    gap: 10px;
    font-size: 14px;
    color: #c0d8ea;
    line-height: 1.6;
  }
  .bullet-list li::before {
    content: '▸';
    color: var(--cyan);
    flex-shrink: 0;
    margin-top: 1px;
    font-size: 12px;
  }

  /* Two-column cards */
  .card-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-bottom: 16px;
  }
  @media(max-width: 700px) { .card-grid { grid-template-columns: 1fr; } }

  /* Code block */
  .code-block {
    background: rgba(0,0,0,0.4);
    border: 1px solid #3a1c63;
    border-radius: 10px;
    padding: 16px 20px;
    
    font-size: 12.5px;
    color: var(--cyan);
    margin: 12px 0;
    overflow-x: auto;
    line-height: 1.8;
    white-space: pre-wrap;
    word-break: break-word;
    overflow-wrap: anywhere;
  }
  .code-comment { color: var(--muted); }

  /* Steps */
  .steps { display: flex; flex-direction: column; gap: 14px; }
  .step {
    display: flex;
    gap: 16px;
    align-items: flex-start;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 18px 22px;
    transition: border-color 0.2s;
  }
  .step:hover { border-color: #5e309d; }
  .step-num {
    width: 32px; height: 32px;
    border-radius: 8px;
    background: var(--cyan-glow);
    border: 1px solid var(--border);
    display: flex; align-items: center; justify-content: center;
    
    font-size: 12px;
    color: var(--cyan);
    flex-shrink: 0;
  }
  .step-body h4 {
    
    font-size: 14px;
    font-weight: 700;
    color: var(--white);
    margin-bottom: 4px;
  }
  .step-body p { font-size: 13.5px; color: var(--muted); line-height: 1.6; }

  /* Note box */
  .note {
    background: #f5a5230b;
    border: 1px solid #f5a6234d;
    border-radius: 10px;
    padding: 14px 18px;
    font-size: 13.5px;
    color: #f5c87a;
    line-height: 1.6;
    margin: 12px 0;
    display: flex;
    gap: 10px;
    align-items: flex-start;
  }
  .note-icon { flex-shrink: 0; margin-top: 1px; }

  /* Diagram (flow) */
  .flow-diagram {
    display: flex;
    align-items: center;
    gap: 6px;
    overflow-x: auto;
    padding: 20px 24px;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 14px;
    margin-bottom: 16px;
  }
  .flow-node {
    background: #432073;
    border: 1px solid #3a1c63;
    border-radius: 8px;
    padding: 10px 16px;
    font-size: 12px;
    font-weight: 600;
    color: var(--white);
    text-align: center;
    white-space: nowrap;
    flex-shrink: 0;
  }
  .flow-node.active {
    background: #3a1c6350;
    border-color: var(--cyan);
    color: var(--cyan);
  }
  .flow-arrow { color: var(--muted); font-size: 18px; flex-shrink: 0; }

  /* Quiz */
  .quiz-section {
    background: #23133a;
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 28px;
    margin-top: 40px;
  }

  .quiz-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
  }
  .quiz-badge {
    background: var(--cyan-glow);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 4px 10px;
    font-size: 10px;
    color: var(--cyan);
    text-transform: uppercase;
  }
  .quiz-title {
    
    font-size: 18px;
    font-weight: 700;
  }

  .quiz-q { margin-bottom: 28px; }
  .quiz-question {
    font-size: 15px;
    font-weight: 600;
    color: var(--white);
    margin-bottom: 14px;
    line-height: 1.5;
  }
  .quiz-options { display: flex; flex-direction: column; gap: 8px; }

  .quiz-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    background: #1f1232;
    border: 1px solid #3a1c63;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    color: #c0d8ea;
    transition: all 0.2s;
    user-select: none;
  }
  .quiz-option:hover { border-color: #3a1c63; background: #2a1647; color: var(--white); }
  .quiz-option.correct { border-color: var(--success); background: rgba(76,222,138,0.1); color: var(--success); }
  .quiz-option.wrong { border-color: #ff6b6b; background: rgba(255,107,107,0.1); color: #ff9999; }
  .quiz-option.disabled { pointer-events: none; opacity: 0.5; }
  .quiz-option.disabled.correct { opacity: 1; }

  .option-letter {
    width: 26px; height: 26px;
    border-radius: 6px;
    background: rgba(255,255,255,0.06);
    display: flex; align-items: center; justify-content: center;
    
    font-size: 11px;
    color: var(--muted);
    flex-shrink: 0;
  }

  .quiz-feedback {
    display: none;
    margin-top: 10px;
    padding: 10px 14px;
    border-radius: 8px;
    font-size: 13.5px;
    line-height: 1.5;
  }
  .quiz-feedback.show { display: block; }
  .quiz-feedback.correct { background: rgba(76,222,138,0.1); color: #4cde8a; border: 1px solid rgba(76,222,138,0.25); }
  .quiz-feedback.wrong { background: rgba(255,107,107,0.1); color: #ff9999; border: 1px solid rgba(255,107,107,0.25); }

  /* Score */
  .quiz-score {
    display: none;
    text-align: center;
    padding: 24px;
    border-top: 1px solid var(--border);
    margin-top: 20px;
  }
  .quiz-score.show { display: block; }
  .score-num {
    
    font-size: 52px;
    font-weight: 800;
    line-height: 1;
    color: var(--cyan);
    margin-bottom: 8px;
  }
  .score-label { font-size: 14px; color: var(--muted); margin-bottom: 20px; }

  .btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    border-radius: 8px;
    
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
  }
  .btn-primary {
    background: var(--cyan);
    color: var(--navy);
    z-index: 1;
  }
  .btn-primary:hover { background: #883cf0e0; transform: translateY(-1px); }
  .btn-secondary {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--muted);
  }
  .btn-secondary:hover { border-color: var(--cyan); color: var(--cyan); }

  /* Tab nav */
  .tab-nav {
    display: flex;
    gap: 4px;
    background: rgba(0,0,0,0.2);
    border-radius: 10px;
    padding: 4px;
    margin-bottom: 24px;
    border: 1px solid var(--border);
  }
  .tab-btn {
    flex: 1;
    padding: 9px 14px;
    border-radius: 7px;
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    border: none;
    background: transparent;
    color: var(--muted);
    transition: all 0.2s;
  }
  .tab-btn.active { background: var(--navy-light); color: var(--cyan); }

  .tab-content { display: none; }
  .tab-content.active { display: block; }

  /* Page navigation */
  .page-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 56px;
    padding-top: 28px;
    border-top: 1px solid var(--border);
  }
  .page-nav-info {  font-size: 11px; color: var(--muted); }

  /* Hidden pages */
  .strongdm-201-training-guide .page { display: none; }
  .strongdm-201-training-guide .page.active { display: block; }

  /* Ref link */
  .ref-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    
    font-size: 11px;
    color: var(--cyan);
    text-decoration: none;
    padding: 4px 10px;
    border: 1px solid #3a1c63;
    border-radius: 5px;
    margin-top: 8px;
    transition: all 0.2s;
  }
  .ref-link:hover { border-color: var(--cyan); background: var(--cyan-glow); }

  /* Keyframes */
  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(20px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  /* Scrollbar */
  ::-webkit-scrollbar { width: 6px; height: 6px; }
  ::-webkit-scrollbar-track { background: transparent; }
  ::-webkit-scrollbar-thumb { background: #873cf015; border-radius: 99px; }

  /* ── MOBILE SIDEBAR (OFF-CANVAS) ── */
  .strongdm-201-training-guide .mobile-topbar {
    display: none;
    position: sticky;
    top: 0;
    z-index: 1;
    height: 56px;
    padding: 0 16px;
    background: #180f26;
    border-bottom: 1px solid var(--border);
    backdrop-filter: blur(12px);
    align-items: center;
    gap: 12px;
    pointer-events: auto;
  }
  .mobile-title {
    min-width: 0;
    
    font-weight: 800;
    font-size: 0.92rem;
    color: var(--white);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  .menu-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 38px;
    height: 34px;
    border-radius: 10px;
    background: transparent;
    border: 1px solid #3a1c63;
    color: var(--white);
    cursor: pointer;
    flex-shrink: 0;
    position: relative;
    z-index: 1;
    pointer-events: auto;
    touch-action: manipulation;
    transition: border-color 0.2s, background 0.2s, transform 0.2s;
  }
  .menu-btn:hover { border-color: #5e309d; background: var(--cyan-glow); }
  .menu-btn:active { transform: translateY(1px); }
  .menu-btn svg { width: 18px; height: 18px; }

  .sidebar-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(0,0,0,0.55);
    z-index: 1;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease;
  }
  body.sidebar-open .sidebar-backdrop {
    opacity: 1;
    pointer-events: auto;
  }

  @media (max-width: 900px) {
    .strongdm-201-training-guide .mobile-topbar {
      display: flex;
      position: absolute;
      width: 100%;
      left: 0;
      right: 0;
    }
    .shell { display: block; padding-top: 56px; }
    .main { max-width: none; padding: 32px 20px; }
    .strongdm-201-training-guide .sidebar {
      position: absolute;
      top: 56px;
      bottom: 0;
      left: 0;
      height: auto;
      width: min(320px, 86vw);
      transform: translateX(-110%);
      transition: transform 0.22s ease;
      z-index: 1;
      box-shadow: 0 12px 40px rgba(0, 0, 0, 0.45);
    }
    body.sidebar-open .strongdm-201-training-guide .sidebar { transform: translateX(0); }
    body.sidebar-open { overflow: hidden; }
  }

  /* ── RESPONSIVE HELPERS ── */
  img, video, canvas, svg { max-width: 100%; height: auto; }
  table { max-width: 100%; }
  @media (max-width: 720px) {
    .module-title {
      font-size: clamp(28px, 9vw, 38px);
      line-height: 1.1;
      word-break: normal;
      overflow-wrap: anywhere;
    }
    .code-block {
      padding: 12px 14px;
      font-size: 11.5px;
    }
    .step { flex-direction: column; gap: 10px; }
    .page-nav { flex-direction: column; align-items: stretch; gap: 10px; }
    .page-nav .btn { width: 100%; justify-content: center; }
    .page-nav-info { text-align: center; }
    table { display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }
  }
  pre { max-width: 100%; overflow-x: auto; }