:root {
    --bg: #23133a;
    --surface: #23133a;
    --surface2: #1f1232;
    --border: #3a1c63;
    --green: #883CF0;
    --green-dim: #873cf0cc;
    --green-glow: #873cf0cc;
    --cyan: #883CF0;
    --amber: #ffb800;
    --red: #ff4d6a;
    --text: #e9f0f7;
    --text-muted: #d6d6d6;
    --text-dim: #d6d6d6;
  }

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

  html { scroll-behavior: smooth; }

  .dart-training-guide {
    background: #191127;
    color: var(--text);
    font-weight: 300;
    line-height: 1.6;
    height: 100vh;
    overflow-y: auto;
    overflow-x: hidden;
  }

  /* ── NOISE OVERLAY ── */
  .dart-training-guide::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.03'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 0;
    opacity: 0.4;
  }

  ::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: #873cf015; }
::-webkit-scrollbar-thumb { background: #873cf015; border-radius: 3px; }

  /* ── HERO ── */
  .hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 4rem 2rem 6rem;
    overflow: hidden;
  }

  .hero-grid {
    position: absolute;
    inset: 0;
    background-image:
      linear-gradient(rgba(104, 0, 232, 0.04) 1px, transparent 1px),
      linear-gradient(90deg, rgba(139, 0, 232, 0.04) 1px, transparent 1px);
    background-size: 48px 48px;
    mask-image: radial-gradient(ellipse 80% 70% at 50% 50%, black 20%, transparent 100%);
  }

  .hero-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    pointer-events: none;
  }
  .orb-1 { width: 500px; height: 500px; background: #1d1823; top: -100px; left: -100px; }
  .orb-2 { width: 400px; height: 400px; background: #0f0818; bottom: -80px; right: -80px; }

  .hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: #2a1647;
    border: 1px solid #3a1c63;
    border-radius: 100px;
    padding: 6px 16px;
    font-size: 11px;
    color: var(--green);
    text-transform: uppercase;
    margin-bottom: 2rem;
    animation: fadeInDown 0.6s ease both;
  }
  .badge-dot {
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--green);
    box-shadow: 0 0 8px var(--green);
    animation: pulse 2s ease infinite;
  }

  .hero-title {
    font-size: clamp(3.5rem, 10vw, 8rem);
    font-weight: 800;
    line-height: 0.95;
    text-align: center;
    position: relative;
    animation: fadeInUp 0.7s 0.1s ease both;
  }
  .hero-title .dart-letter {
    display: inline-block;
    position: relative;
  }
  .hero-title .dart-letter span {
    color: var(--green);
    position: relative;
  }
  .hero-title .dart-letter span::after {
    content: attr(data-word);
    position: absolute;
    left: 100%;
    font-size: 0.28em;
    font-weight: 600;
    color: var(--text-muted);
    top: 0.2em;
    white-space: nowrap;
  }

  .hero-sub {
    
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    font-weight: 600;
    color: var(--text-muted);
    text-align: center;
    margin-top: 1.5rem;
    text-transform: uppercase;
    animation: fadeInUp 0.7s 0.2s ease both;
  }

  .hero-desc {
    max-width: 640px;
    text-align: center;
    color: #f0f8ff;
    font-size: 1.05rem;
    margin-top: 1.5rem;
    line-height: 1.7;
    animation: fadeInUp 0.7s 0.3s ease both;
  }

  .hero-stats {
    display: flex;
    gap: 3rem;
    margin-top: 3rem;
    animation: fadeInUp 0.7s 0.4s ease both;
  }
  .stat {
    text-align: center;
  }
  .stat-num {
    
    font-size: 2rem;
    color: var(--green);
    display: block;
    line-height: 1;
  }
  .stat-label {
    font-size: 0.72rem;
    color: var(--text-dim);
    text-transform: uppercase;
    margin-top: 4px;
  }

  .scroll-cue {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--text-dim);
    font-size: 10px;
    text-transform: uppercase;
    animation: fadeInUp 1s 0.8s ease both;
  }
  .scroll-line {
    width: 1px;
    height: 40px;
    background: linear-gradient(to bottom, transparent, var(--green));
    animation: scrollPulse 2s ease infinite;
  }

  /* ── NAV TABS ── */
  .nav-wrapper {
    position: sticky;
    top: 0;
    z-index: 1;
    background: #180f26;
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
    padding: 0 2rem;
  }

  .nav-tabs {
    display: flex;
    gap: 0;
    max-width: 1200px;
    margin: 0 auto;
    overflow-x: auto;
    scrollbar-width: none;
  }
  .nav-tabs::-webkit-scrollbar { display: none; }

  .nav-tab {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 1.1rem 1.8rem;
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-dim);
    background: none;
    border: none;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: all 0.25s ease;
    white-space: nowrap;
    position: relative;
  }
  .nav-tab:hover { color: var(--text); }
  .nav-tab.active { color: var(--green); border-bottom-color: var(--green); }
  .nav-tab .tab-icon { font-size: 1rem; }
  .nav-tab .tab-num {
    
    font-size: 9px;
    color: var(--text-dim);
    margin-right: -4px;
  }

  /* ── MAIN CONTENT ── */
  .main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem 6rem;
  }

  /* ── PHASE SECTIONS ── */
  .phase-section {
    display: none;
    animation: fadeInUp 0.4s ease both;
  }
  .phase-section.active { display: block; }

  /* ── WHY IMPORTANT BANNER ── */
  .why-banner {
    margin: 3rem 0;
    padding: 2.5rem 3rem;
    background: linear-gradient(135deg, #23133a 0%, #1f1232 100%);
    border: 1px solid #3a1c63;
    border-left: 4px solid #3a1c63;
    border-radius: 4px 12px 12px 4px;
    position: relative;
    overflow: hidden;
  }
  .why-banner::before {
    content: '!';
    position: absolute;
    right: 2rem;
    top: 50%;
    transform: translateY(-50%);
    font-size: 8rem;
    font-weight: 800;
    color: #3a1c63;
    line-height: 1;
  }
  .why-label {
    font-size: 10px;
    text-transform: uppercase;
    color: var(--green);
    margin-bottom: 0.75rem;
  }
  .why-title {
    
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 0.75rem;
  }
  .why-text {
    color: #f0f8ff;
    font-size: 1rem;
    max-width: 700px;
    line-height: 1.75;
  }

  /* ── PHASE HEADER ── */
  .phase-header {
    padding: 4rem 0 2rem;
    display: flex;
    align-items: flex-end;
    gap: 2rem;
  }
  .phase-num {
    font-size: 5rem;
    font-weight: 700;
    color: #23133a;
    line-height: 1;
    flex-shrink: 0;
  }

  .phase-tag {
    
    font-size: 10px;
    color: var(--green);
    text-transform: uppercase;
    margin-bottom: 6px;
  }
  .phase-title {
    
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 800;
    line-height: 1;
  }
  .phase-subtitle {
    color: var(--text-muted);
    font-size: 1rem;
    margin-top: 6px;
    font-weight: 400;
  }

  /* ── TOOL CHIPS ── */
  .tool-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 1.5rem 0 2.5rem;
  }
  .chip {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 5px 14px;
    border-radius: 100px;
    font-size: 11px;
    border: 1px solid;
  }
  .chip-green { background: #23133a; border-color: #5e309d; color: var(--green); }
  .chip-cyan { background: #2a1647; border-color: #5e309d; color: var(--cyan); }
  .chip-amber { background: rgba(255,184,0,0.08); border-color: rgba(255,184,0,0.3); color: var(--amber); }

  /* ── CARDS GRID ── */
  .cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
  }

  .card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 1.75rem;
    transition: border-color 0.2s, transform 0.2s;
    cursor: default;
  }
  .card:hover {
    border-color: #5e309d;
    transform: translateY(-2px);
  }
  .card-icon {
    width: 44px;
    height: 44px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
    margin-bottom: 1.1rem;
    background: var(--surface2);
    border: 1px solid var(--border);
  }
  .card-title {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 0.5rem;
  }
  .card-text {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.6;
  }

  /* ── UNCOVER SECTION ── */
  .uncover-section {
    margin: 3rem 0;
    padding: 2rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 16px;
  }
  .uncover-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 1.5rem;
  }
  .uncover-icon {
    width: 36px; height: 36px;
    border-radius: 8px;
    background: rgba(255,184,0,0.1);
    border: 1px solid rgba(255,184,0,0.2);
    display: flex; align-items: center; justify-content: center;
    font-size: 1rem;
  }
  .uncover-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--amber);
  }
  .uncover-subtitle {
    font-size: 0.8rem;
    color: var(--text-dim);
  }

  .uncover-list {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0.75rem;
  }
  .uncover-list li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.875rem;
    color: var(--text-muted);
    padding: 0.75rem 1rem;
    background: var(--surface2);
    border-radius: 8px;
    border: 1px solid var(--border);
  }
  .uncover-list li::before {
    content: '→';
    color: var(--amber);
    
    flex-shrink: 0;
    margin-top: 1px;
  }

  /* ── IMPLICATIONS ── */
  .implication-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
  }
  .implication-card {
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid;
  }
  .impl-risk { background: rgba(255,77,106,0.05); border-color: rgba(255,77,106,0.2); }
  .impl-ops { background: #883cf050; border-color: #3a1c63; }
  .impl-comp { background: rgba(255,184,0,0.05); border-color: rgba(255,184,0,0.2); }
  .impl-arch { background: #3a1c6350; border-color: #5e309d; }

  .impl-tag {
    
    font-size: 9px;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
  }
  .impl-risk .impl-tag { color: var(--red); }
  .impl-ops .impl-tag { color: var(--cyan); }
  .impl-comp .impl-tag { color: var(--amber); }
  .impl-arch .impl-tag { color: var(--green); }

  .impl-text {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.6;
  }

  /* ── PROCESS STEPS ── */
  .process-steps {
    display: flex;
    flex-direction: column;
    gap: 0;
    margin: 2rem 0;
    position: relative;
  }
  .process-steps::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 1px;
    background: linear-gradient(to bottom, var(--green), transparent);
    opacity: 0.3;
  }
  .process-step {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem 1.5rem 1.5rem 0;
    position: relative;
  }
  .step-num {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--surface2);
    border: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    color: var(--green);
    flex-shrink: 0;
    position: relative;
    z-index: 1;
  }

  .step-title {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 4px;
  }
  .step-text {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.6;
  }

  /* ── SECTION DIVIDER ── */
  .section-divider {
    height: 1px;
    background: linear-gradient(to right, transparent, var(--border), transparent);
    margin: 2.5rem 0;
  }

  .section-label {
    font-size: 10px;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-bottom: 1.25rem;
    display: flex;
    align-items: center;
    gap: 12px;
  }
  .section-label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
  }

  /* ── OVERVIEW PHASE ── */
  .dart-flow {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1px;
    background: var(--border);
    border-radius: 16px;
    overflow: hidden;
    margin: 3rem 0;
  }
  .flow-phase {
    background: var(--surface);
    padding: 2rem 1.5rem;
    cursor: pointer;
    transition: background 0.2s;
    position: relative;
    overflow: hidden;
  }
  .flow-phase::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--green);
    transform: scaleX(0);
    transition: transform 0.3s ease;
    transform-origin: left;
  }
  .flow-phase:hover { background: var(--surface2); }
  .flow-phase:hover::after { transform: scaleX(1); }
  .flow-letter {
    
    font-size: 3rem;
    font-weight: 800;
    color: var(--green);
    line-height: 1;
    opacity: 0.4;
  }
  .flow-word {
    
    font-size: 0.95rem;
    font-weight: 700;
    margin: 0.5rem 0 0.25rem;
  }
  .flow-desc {
    font-size: 0.78rem;
    color: var(--text-dim);
    line-height: 1.5;
  }

  /* ── CALLOUT ── */
  .callout {
    padding: 1.25rem 1.5rem;
    border-radius: 10px;
    margin: 1.5rem 0;
    display: flex;
    gap: 12px;
    align-items: flex-start;
  }
  .callout-info { background: #23133a; border: 1px solid #3a1c63; }
  .callout-warn { background: rgba(255,184,0,0.07); border: 1px solid rgba(255,184,0,0.2); }
  .callout-icon { font-size: 1.1rem; flex-shrink: 0; margin-top: 2px; }
  .callout-text { font-size: 0.9rem; color: var(--text-muted); line-height: 1.6; }
  .callout-text strong { color: var(--text); }

  /* ── FOOTER ── */
  .training-footer {
    border-top: 1px solid var(--border);
    padding: 3rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
    flex-wrap: wrap;
  }
  .footer-brand {
    font-weight: 800;
    font-size: 1.1rem;
    color: var(--green);
  }
  .footer-text {
    font-size: 0.8rem;
    color: var(--text-dim);
  }
  .progress-bar-wrapper {
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    z-index: 1;
    background: #282035;
  }
  .progress-bar {
    height: 100%;
    background: #3a1c63;
    box-shadow: 0 0 8px #be52e50f;
    width: 0%;
    transition: width 0.1s linear;
  }

  /* ── ANIMATIONS ── */
  @keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-16px); }
    to { opacity: 1; transform: translateY(0); }
  }
  @keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }
  @keyframes pulse {
    0%, 100% { opacity: 1; box-shadow: 0 0 8px var(--green); }
    50% { opacity: 0.5; box-shadow: 0 0 4px var(--green); }
  }
  @keyframes scrollPulse {
    0% { opacity: 0; transform: scaleY(0); transform-origin: top; }
    50% { opacity: 1; transform: scaleY(1); }
    100% { opacity: 0; transform: scaleY(1); transform-origin: bottom; }
  }

  /* ── RESPONSIVE ── */
  @media (max-width: 768px) {
    .dart-flow { grid-template-columns: repeat(2, 1fr); }
    .phase-header { flex-direction: column; gap: 0.5rem; }
    .phase-num { font-size: 3rem; }
    .hero-stats { gap: 2rem; }
    .why-banner { padding: 1.75rem; }
  }
  @media (max-width: 480px) {
    .dart-flow { grid-template-columns: 1fr; }
    .nav-tab { padding: 1rem 1rem; }
    .nav-tab span.tab-label { display: none; }
  }