:root {
    --bg: #0d0d14; --card: #13131f; --border: #1e1e30;
    --yellow: #f5c842; --blue: #4fa8ff; --green: #4dffb0;
    --pink: #ff6b9d; --purple: #b87aff; --orange: #ff9f4a;
    --text: #e8e8f0; --muted: #7070a0; --sidebar-w: 260px;
  }

  section {
  margin-left: auto;
  margin-right: auto;
}

  * { box-sizing: border-box; margin: 0; padding: 0; }
  html { scroll-behavior: smooth; }

  body {
    background: var(--bg); color: var(--text);
    font-family: 'Syne', sans-serif; min-height: 100vh; overflow-x: hidden;
  }

  body::before {
    content: ''; position: fixed; inset: 0;
    background-image:
      linear-gradient(rgba(79,168,255,0.04) 1px, transparent 1px),
      linear-gradient(90deg, rgba(79,168,255,0.04) 1px, transparent 1px);
    background-size: 40px 40px; pointer-events: none; z-index: 0;
  }

  /* ===== TOP NAV ===== */
  nav.topnav {
    position: fixed; top: 0; left: 0; right: 0; z-index: 200;
    background: rgba(13,13,20,0.92); backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border); padding: 0 24px;
    height: 56px; display: flex; align-items: center; justify-content: space-between;
  }

  .nav-logo {
    font-family: 'JetBrains Mono', monospace; font-weight: 700;
    font-size: 15px; color: var(--yellow); text-decoration: none; white-space: nowrap;
  }
  .nav-logo span { color: var(--muted); }

  .nav-right { display: flex; align-items: center; gap: 20px; }

  .nav-links { display: flex; gap: 24px; list-style: none; }
  .nav-links a {
    font-family: 'JetBrains Mono', monospace; font-size: 11px;
    color: var(--muted); text-decoration: none; letter-spacing: 1px; transition: color 0.2s;
  }
  .nav-links a:hover { color: var(--text); }

  .hamburger {
    display: none; flex-direction: column; gap: 5px; cursor: pointer;
    padding: 6px; background: none; border: 1px solid var(--border); border-radius: 8px;
  }
  .hamburger span { display: block; width: 20px; height: 2px; background: var(--muted); border-radius: 2px; }

  @media (max-width: 900px) { .nav-links { display: none; } .hamburger { display: flex; } }

  /* ===== LAYOUT ===== */
  .layout { display: flex; padding-top: 56px; min-height: 100vh; }

  /* ===== SIDEBAR ===== */
  .sidebar {
    position: fixed; top: 56px; left: 0; width: var(--sidebar-w);
    height: calc(100vh - 56px); overflow-y: auto;
    background: rgba(13,13,20,0.97); border-right: 1px solid var(--border);
    padding: 20px 0 40px; z-index: 100; transition: transform 0.3s ease;
  }

  .sidebar::-webkit-scrollbar { width: 3px; }
  .sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }

  /* Back button */
  .sidebar-back {
    display: flex; align-items: center; gap: 8px;
    margin: 0 14px 16px;
    padding: 9px 14px;
    background: rgba(255,255,255,0.04);
    border: 1px solid var(--border);
    border-radius: 10px;
    font-family: 'JetBrains Mono', monospace; font-size: 11px;
    color: var(--muted); text-decoration: none;
    transition: border-color 0.2s, color 0.2s, background 0.2s;
  }
  .sidebar-back:hover { border-color: var(--yellow); color: var(--yellow); background: rgba(245,200,66,0.06); }
  .sidebar-back-arrow { font-size: 14px; }

  .sidebar-divider { height: 1px; background: var(--border); margin: 10px 16px; }

  .sidebar-section-label {
    font-family: 'JetBrains Mono', monospace; font-size: 9px;
    letter-spacing: 3px; text-transform: uppercase; color: var(--muted);
    padding: 0 16px; margin-bottom: 5px; margin-top: 16px;
  }
  .sidebar-section-label:first-of-type { margin-top: 0; }

  .sidebar-link {
    display: flex; align-items: center; gap: 9px; padding: 8px 16px;
    font-family: 'JetBrains Mono', monospace; font-size: 11px; color: var(--muted);
    text-decoration: none; border-left: 2px solid transparent;
    transition: color 0.2s, background 0.2s, border-left-color 0.2s;
  }
  .sidebar-link:hover { color: var(--text); background: rgba(255,255,255,0.03); border-left-color: var(--border); }
  .sidebar-link.active { color: var(--green); background: rgba(77,255,176,0.05); border-left-color: var(--green); }
  .sidebar-link.lp-link.active { color: var(--yellow); background: rgba(245,200,66,0.05); border-left-color: var(--yellow); }

  .s-icon { font-size: 13px; width: 16px; text-align: center; flex-shrink: 0; }
  .s-badge { margin-left: auto; font-size: 9px; padding: 1px 5px; border-radius: 8px; background: rgba(77,255,176,0.12); color: var(--green); }

  .sidebar-overlay {
    display: none; position: fixed; inset: 0; top: 56px;
    background: rgba(0,0,0,0.6); z-index: 99;
  }

  @media (max-width: 900px) {
    .sidebar { transform: translateX(-100%); }
    .sidebar.open { transform: translateX(0); }
    .sidebar-overlay.open { display: block; }
  }

  /* ===== MAIN ===== */
  .main { margin-left: var(--sidebar-w); flex: 1; min-width: 0; position: relative; z-index: 1; }
  @media (max-width: 900px) { .main { margin-left: 0; } }

  section { padding: 68px 48px; max-width: 820px; }
  #hero { padding: 76px 48px 60px; max-width: 100%; text-align: center; }
  #cta  { padding: 60px 48px 76px; max-width: 100%; text-align: center; }

  @media (max-width: 600px) {
    section { padding: 50px 20px; }
    #hero   { padding: 56px 20px 44px; }
    #cta    { padding: 44px 20px 60px; }
  }

  /* ===== HERO ===== */
  .hero-badge {
    display: inline-block; background: rgba(77,255,176,0.1);
    border: 1px solid rgba(77,255,176,0.25); color: var(--green);
    font-size: 11px; letter-spacing: 3px; text-transform: uppercase;
    padding: 6px 16px; border-radius: 20px; margin-bottom: 22px;
    font-family: 'JetBrains Mono', monospace; animation: fadeDown 0.6s ease both;
  }

  .hero-title {
    font-size: clamp(2.8rem, 8vw, 5rem); font-weight: 800; line-height: 1;
    background: linear-gradient(135deg, #4dffb0 0%, #4fa8ff 50%, #b87aff 100%);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
    animation: fadeDown 0.6s ease 0.1s both;
  }

  .hero-sub {
    font-size: 1rem; color: var(--muted); margin-top: 12px;
    font-family: 'JetBrains Mono', monospace; animation: fadeDown 0.6s ease 0.2s both;
  }

  .hero-code {
    display: inline-block; margin-top: 30px; background: #080810;
    border: 1px solid var(--border); border-radius: 14px; padding: 20px 28px;
    font-family: 'JetBrains Mono', monospace; font-size: 13px; line-height: 2;
    text-align: left; animation: fadeUp 0.6s ease 0.3s both;
  }

  .hero-buttons {
    display: flex; gap: 12px; justify-content: center;
    margin-top: 28px; flex-wrap: wrap; animation: fadeUp 0.6s ease 0.4s both;
  }

  .btn {
    padding: 11px 22px; border-radius: 10px; font-family: 'JetBrains Mono', monospace;
    font-size: 12px; font-weight: 700; text-decoration: none; cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s; border: none; display: inline-block;
  }
  .btn:hover { transform: translateY(-2px); }
  .btn-primary { background: var(--green); color: #0d0d14; box-shadow: 0 4px 20px rgba(77,255,176,0.2); }
  .btn-outline  { background: transparent; color: var(--text); border: 1px solid var(--border); }
  .btn-outline:hover { border-color: var(--blue); color: var(--blue); }

  /* ===== SHARED ===== */
  .section-label   { font-size: 10px; letter-spacing: 3px; text-transform: uppercase; color: var(--muted); font-family: 'JetBrains Mono', monospace; margin-bottom: 10px; }
  .section-heading { font-size: clamp(1.4rem, 3vw, 2rem); font-weight: 800; line-height: 1.15; margin-bottom: 12px; }
  .section-desc    { color: var(--muted); font-size: 14px; line-height: 1.75; max-width: 580px; }

  .divider { height: 1px; background: linear-gradient(90deg, transparent, var(--border), transparent); margin: 0 48px; }
  @media (max-width: 600px) { .divider { margin: 0 20px; } }

  /* ===== GRIDS ===== */
  .grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 28px; }
  .grid-3 { display: grid; grid-template-columns: repeat(3,1fr); gap: 12px; margin-top: 28px; }

  @media (max-width: 700px) { .grid-2 { grid-template-columns: 1fr; } .grid-3 { grid-template-columns: 1fr 1fr; } }
  @media (max-width: 440px) { .grid-3 { grid-template-columns: 1fr; } }

  /* ===== CARDS ===== */
  .card { background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 20px; transition: transform 0.2s, border-color 0.2s; }
  .card:hover { transform: translateY(-3px); }
  .card-icon  { font-size: 22px; margin-bottom: 8px; }
  .card-title { font-weight: 700; font-size: 14px; margin-bottom: 5px; }
  .card-text  { color: var(--muted); font-size: 12px; line-height: 1.65; }
  .card.c-green:hover  { border-color: rgba(77,255,176,0.35); }
  .card.c-blue:hover   { border-color: rgba(79,168,255,0.35); }
  .card.c-yellow:hover { border-color: rgba(245,200,66,0.35); }
  .card.c-pink:hover   { border-color: rgba(255,107,157,0.35); }
  .card.c-purple:hover { border-color: rgba(184,122,255,0.35); }
  .card.c-orange:hover { border-color: rgba(255,159,74,0.35); }

  /* ===== CODE BLOCK ===== */
  .code-block {
    background: #080810; border: 1px solid var(--border); border-radius: 12px;
    padding: 20px 24px; font-family: 'JetBrains Mono', monospace;
    font-size: 13px; line-height: 1.9; margin-top: 16px; overflow-x: auto;
  }

  .code-block .line { display: block; white-space: pre; }
  .code-block .line-num { color: #30304a; margin-right: 18px; user-select: none; font-size: 11px; }

  /* Syntax colors */
  .kw   { color: var(--pink);   font-weight: 700; }
  .fn   { color: var(--yellow); font-weight: 700; }
  .str  { color: var(--green); }
  .cmt  { color: #404060; font-style: italic; }
  .num  { color: var(--orange); }
  .var  { color: var(--text); }
  .op   { color: var(--muted); }
  .prm  { color: var(--blue); }
  .cls  { color: var(--purple); font-weight: 700; }
  .ind  { display: inline-block; width: 24px; }

  /* Code header bar */
  .code-header {
    display: flex; align-items: center; justify-content: space-between;
    background: #0a0a15; border: 1px solid var(--border);
    border-bottom: none; border-radius: 12px 12px 0 0;
    padding: 10px 18px; margin-top: 16px;
  }

  .code-header + .code-block { margin-top: 0; border-radius: 0 0 12px 12px; }

  .code-dots { display: flex; gap: 6px; }
  .code-dot  { width: 10px; height: 10px; border-radius: 50%; }

  .code-filename { font-family: 'JetBrains Mono', monospace; font-size: 11px; color: var(--muted); }

  /* ===== SYNTAX TABLE ===== */
  .syntax-table { width: 100%; border-collapse: collapse; margin-top: 20px; font-size: 13px; }

  .syntax-table th {
    padding: 10px 14px; text-align: left; color: var(--muted);
    font-family: 'JetBrains Mono', monospace; font-size: 10px;
    letter-spacing: 2px; text-transform: uppercase;
    border-bottom: 1px solid var(--border); background: rgba(255,255,255,0.02);
  }

  .syntax-table td {
    padding: 11px 14px; border-bottom: 1px solid rgba(255,255,255,0.04);
    vertical-align: top; line-height: 1.5;
  }

  .syntax-table tr:last-child td { border-bottom: none; }
  .syntax-table tr:hover td { background: rgba(255,255,255,0.02); }

  .syntax-table code {
    font-family: 'JetBrains Mono', monospace; font-size: 12px;
    color: var(--green); background: rgba(77,255,176,0.08);
    padding: 2px 7px; border-radius: 5px;
  }

  .td-muted { color: var(--muted); font-size: 12px; }

  /* ===== OPERATOR BADGES ===== */
  .op-grid { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 20px; }

  .op-badge {
    display: flex; align-items: center; gap: 10px;
    background: var(--card); border: 1px solid var(--border);
    border-radius: 10px; padding: 10px 14px;
    font-family: 'JetBrains Mono', monospace; font-size: 12px;
    transition: border-color 0.2s, transform 0.15s;
    min-width: 120px;
  }
  .op-badge:hover { border-color: var(--blue); transform: translateY(-2px); }
  .op-sym  { color: var(--yellow); font-weight: 700; font-size: 15px; min-width: 22px; text-align: center; }
  .op-desc { color: var(--muted); font-size: 11px; }

  /* ===== ANNOTATION CARDS ===== */
  .ann-list { margin-top: 20px; display: flex; flex-direction: column; gap: 10px; }

  .ann-item {
    display: flex; align-items: flex-start; gap: 14px;
    background: var(--card); border: 1px solid var(--border);
    border-radius: 12px; padding: 16px 18px;
    transition: border-color 0.2s, transform 0.2s;
  }
  .ann-item:hover { transform: translateX(4px); }

  .ann-dot-wrap { padding-top: 3px; }
  .ann-dot { width: 9px; height: 9px; border-radius: 50%; flex-shrink: 0; }

  .ann-kw   { font-family: 'JetBrains Mono', monospace; font-size: 13px; font-weight: 700; margin-bottom: 3px; }
  .ann-desc { color: var(--muted); font-size: 12px; line-height: 1.55; }
  .ann-ex   { display: inline-block; margin-top: 5px; font-family: 'JetBrains Mono', monospace; font-size: 11px; color: var(--green); background: rgba(77,255,176,0.08); padding: 2px 8px; border-radius: 5px; }

  /* ===== RULE CARD ===== */
  .rule-card {
    margin-top: 24px;
    background: linear-gradient(135deg, rgba(77,255,176,0.07), rgba(79,168,255,0.07));
    border: 1px solid rgba(77,255,176,0.2); border-radius: 14px;
    padding: 20px 24px; display: flex; align-items: center; gap: 14px;
  }
  .rule-icon { font-size: 26px; flex-shrink: 0; }
  .rule-text { font-size: 14px; line-height: 1.55; }
  .rule-text strong { color: var(--green); }

  /* ===== CTA ===== */
  .cta-box {
    background: linear-gradient(135deg, rgba(77,255,176,0.07), rgba(79,168,255,0.07));
    border: 1px solid rgba(77,255,176,0.18); border-radius: 20px;
    padding: 50px 36px; max-width: 560px; margin: 0 auto;
  }
  .cta-title {
    font-size: clamp(1.5rem, 4vw, 2.4rem); font-weight: 800; margin-bottom: 12px;
    background: linear-gradient(135deg, var(--green), var(--blue));
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
  }
  .cta-text { color: var(--muted); font-size: 14px; line-height: 1.7; margin-bottom: 22px; }

  footer {
    border-top: 1px solid var(--border); padding: 22px 48px;
    text-align: center; font-family: 'JetBrains Mono', monospace;
    font-size: 12px; color: var(--muted); position: relative; z-index: 1;
  }
  footer span { color: var(--green); }

  /* ===== PROGRESS BAR ===== */
  .progress-bar {
    position: fixed; top: 56px; left: var(--sidebar-w); right: 0; height: 2px;
    background: linear-gradient(90deg, var(--green), var(--blue), var(--purple));
    transform-origin: left; transform: scaleX(0); z-index: 199;
  }
  @media (max-width: 900px) { .progress-bar { left: 0; } }

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

  .fade-in { opacity: 0; transform: translateY(18px); transition: opacity 0.55s ease, transform 0.55s ease; }
  .fade-in.visible { opacity: 1; transform: translateY(0); }