:root {
    --primary: #573AFC;
    --primary-active: #4527E0;
    --primary-focus: #6B4FFF;
    --primary-disabled: #D6D6D6;
    --ink: #1d1d1f;
    --body-c: #3c3c3c;
    --body-strong: #1a1a1a;
    --muted: #6b6b6b;
    --muted-soft: #9a9a9a;
    --hairline: #e6e6e6;
    --hairline-strong: #cccccc;
    --canvas: #ffffff;
    --canvas-parchment: #f5f5f7;
    --surface-soft: #f7f7f7;
    --surface-card: #fafafa;
    --surface-strong: #ebebeb;
    --surface-dark: #1a2129;
    --surface-tile-1: #272729;
    --on-primary: #ffffff;
    --on-dark: #ffffff;
    --on-dark-soft: #bbbbbb;
    --success: #22c55e;
    --warning: #f59e0b;
    --error: #dc2626;
    --product-shadow: rgba(0,0,0,0.22) 3px 5px 30px;
  }
  [data-theme="dark"] {
    --ink: #f5f5f7;
    --body-c: #d1d1d6;
    --body-strong: #ffffff;
    --muted: #8e8e93;
    --muted-soft: #636366;
    --hairline: #2c2c2e;
    --hairline-strong: #3a3a3c;
    --canvas: #0e0e10;
    --canvas-parchment: #161618;
    --surface-soft: #1a1a1c;
    --surface-card: #1c1c1e;
    --surface-strong: #2c2c2e;
    --surface-dark: #000000;
    --primary: #9A7AFB;
    --primary-active: #7c5cf5;
  }

  * { box-sizing: border-box; margin: 0; padding: 0; }
  html { scroll-behavior: smooth; }
  body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    color: var(--body-c);
    background: var(--canvas);
    -webkit-font-smoothing: antialiased;
    transition: background .25s ease, color .25s ease;
  }
  img { max-width: 100%; display: block; }
  a { color: inherit; text-decoration: none; }
  button { font-family: inherit; cursor: pointer; }
  .container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
  section { padding: 80px 0; }
  .hidden { display: none !important; }

  h1, h2, h3 { color: var(--body-strong); font-weight: 700; letter-spacing: -0.2px; }
  .hero-display { font-size: 56px; line-height: 1.07; letter-spacing: -0.28px; }
  .display-lg { font-size: 40px; line-height: 1.1; }
  .display-sm { font-size: 24px; line-height: 1.25; }
  .lead { font-size: 22px; line-height: 1.4; font-weight: 400; }
  .body-md { font-size: 17px; line-height: 1.5; letter-spacing: -0.1px; }
  .caption { font-size: 14px; line-height: 1.43; color: var(--muted); }
  .label-uppercase { font-size: 13px; font-weight: 700; line-height: 1.3; letter-spacing: 1.5px; text-transform: uppercase; color: var(--primary); }
  .fine-print { font-size: 12px; color: var(--muted); }

  /* ---------- Buttons ---------- */
  .btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; height: 48px; padding: 0 28px; border-radius: 9999px; font-size: 15px; font-weight: 600; border: none; transition: transform .15s ease, background .15s ease; white-space: nowrap; }
  .btn:active { transform: scale(0.95); }
  .btn-primary { background: var(--primary); color: var(--on-primary); }
  .btn-primary:hover { background: var(--primary-active); }
  .btn-primary:disabled { background: var(--primary-disabled); cursor: not-allowed; transform: none; }
  .btn-secondary { background: var(--canvas); color: var(--ink); border: 1px solid var(--hairline-strong); }
  .btn-secondary-on-dark { background: transparent; color: var(--on-dark); border: 1px solid rgba(255,255,255,0.4); }
  .btn-icon { width: 44px; height: 44px; padding: 0; border-radius: 9999px; background: transparent; border: 1px solid var(--hairline); color: var(--ink); display: inline-flex; align-items: center; justify-content: center; }
  .icon { width: 20px; height: 20px; stroke: currentColor; fill: none; stroke-width: 1.75; stroke-linecap: round; stroke-linejoin: round; }

  /* ---------- Nav ---------- */
  .nav { position: sticky; top: 0; z-index: 40; height: 64px; background: var(--canvas); border-bottom: 1px solid var(--hairline); }
  .nav.scrolled { backdrop-filter: blur(20px) saturate(180%); background: color-mix(in srgb, var(--canvas) 82%, transparent); }
  .nav-inner { display: flex; align-items: center; justify-content: space-between; height: 100%; }
  .nav-brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 17px; color: var(--ink); }
  .nav-brand img { width: 28px; height: 28px; }
  .nav-links { display: flex; align-items: center; gap: 28px; font-size: 14px; font-weight: 500; letter-spacing: 0.2px; }
  .nav-links a { color: var(--muted); }
  .nav-links a:hover { color: var(--ink); }
  .nav-right { display: flex; align-items: center; gap: 12px; }
  #navUsageBadge { font-size: 12px; }
  @media (max-width: 560px) { #navUsageBadge { display: none; } }
  .nav-toggle { display: none; }

  @media (max-width: 419px) {
    .nav-links { position: fixed; top: 64px; left: 0; right: 0; background: var(--canvas); border-bottom: 1px solid var(--hairline); flex-direction: column; align-items: flex-start; padding: 16px 24px; gap: 18px; transform: translateY(-8px); opacity: 0; pointer-events: none; transition: .2s ease; }
    .nav-links.open { transform: translateY(0); opacity: 1; pointer-events: auto; }
    .nav-toggle { display: inline-flex; }
  }

  /* ---------- Hero + Generator ---------- */
  .hero { background: var(--surface-dark); padding: 72px 0 96px; }
  .hero-inner { text-align: center; max-width: 760px; margin: 0 auto 48px; }
  .hero .label-uppercase { display: block; margin-bottom: 16px; }
  .hero h1 { color: #fff; margin-bottom: 18px; }
  .hero .lead { color: var(--on-dark-soft); }

  .generator-card { max-width: 780px; margin: 0 auto; background: var(--surface-card); border-radius: 18px; padding: 8px; box-shadow: var(--product-shadow); }
  .format-tabs { display: flex; gap: 6px; padding: 8px; }
  .format-tab { flex: 1; padding: 12px 8px; border-radius: 9999px; border: none; background: transparent; color: var(--muted); font-size: 14px; font-weight: 600; display: flex; align-items: center; justify-content: center; gap: 6px; transition: .15s ease; }
  .format-tab.active { background: var(--primary); color: #fff; }
  .format-tab .icon { width: 17px; height: 17px; }

  .generator-body { padding: 8px 16px 16px; }
  .prompt-input { width: 100%; min-height: 108px; resize: vertical; border: 1px solid var(--hairline); border-radius: 8px; padding: 14px 16px; font-family: inherit; font-size: 16px; color: var(--ink); background: var(--canvas); }
  .prompt-input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 18%, transparent); }

  .chips { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0; }
  .chip { padding: 8px 14px; border-radius: 9999px; border: 1px solid var(--hairline); background: var(--canvas); color: var(--muted); font-size: 13px; font-weight: 500; }
  .chip:hover { border-color: var(--primary); color: var(--primary); }

  .generator-actions { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 8px; flex-wrap: wrap; }
  .generator-actions .btn { flex-shrink: 0; }

  .result-panel { max-width: 780px; margin: 20px auto 0; background: var(--canvas); border: 1px solid var(--hairline); border-radius: 18px; padding: 24px; text-align: left; }
  .result-panel h3 { margin-bottom: 6px; }
  .result-meta { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 18px; flex-wrap: wrap; }
  .result-body { color: var(--body-c); font-size: 15px; line-height: 1.6; max-height: 220px; overflow: auto; padding-right: 4px; }
  .result-body h4 { font-size: 15px; margin: 14px 0 4px; color: var(--body-strong); }
  .result-body h5 { font-size: 14px; margin: 10px 0 2px; color: var(--body-strong); }
  .result-body ul { padding-left: 20px; margin: 4px 0 10px; }
  .result-body li { margin-bottom: 4px; }
  .stream-preview { max-width: 780px; margin: 14px auto 0; background: var(--surface-dark); color: var(--on-dark-soft); border-radius: 14px; padding: 16px 18px; font-family: 'SFMono-Regular', Consolas, monospace; font-size: 12.5px; line-height: 1.6; max-height: 160px; overflow: auto; white-space: pre-wrap; word-break: break-word; }
  .demo-badge { display: inline-flex; align-items: center; gap: 6px; padding: 4px 10px; border-radius: 9999px; background: color-mix(in srgb, var(--warning) 15%, transparent); color: var(--warning); font-size: 12px; font-weight: 600; }
  .spinner { width: 16px; height: 16px; border: 2px solid rgba(255,255,255,0.4); border-top-color: #fff; border-radius: 50%; animation: spin .7s linear infinite; }
  @keyframes spin { to { transform: rotate(360deg); } }

  /* ---------- Feature grid ---------- */
  .section-parchment { background: var(--canvas-parchment); }
  .section-head { text-align: center; max-width: 620px; margin: 0 auto 48px; }
  .section-head .label-uppercase { display: block; margin-bottom: 12px; }

  .feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
  .feature-card { background: var(--canvas); border: 1px solid var(--hairline); border-radius: 18px; padding: 24px; }
  .feature-card .icon-wrap { width: 44px; height: 44px; border-radius: 9999px; background: color-mix(in srgb, var(--primary) 12%, transparent); color: var(--primary); display: flex; align-items: center; justify-content: center; margin-bottom: 16px; }
  .feature-card h3 { font-size: 17px; margin-bottom: 6px; }
  .feature-card p { font-size: 14px; color: var(--muted); line-height: 1.5; margin-bottom: 14px; }
  .feature-card .learn { font-size: 13px; font-weight: 700; letter-spacing: 1px; text-transform: uppercase; color: var(--ink); }

  /* ---------- How it works ---------- */
  .steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
  .step { text-align: center; }
  .step-num { width: 40px; height: 40px; border-radius: 9999px; background: var(--primary); color: #fff; font-weight: 700; display: flex; align-items: center; justify-content: center; margin: 0 auto 16px; }
  .step h3 { font-size: 18px; margin-bottom: 8px; }
  .step p { font-size: 14px; color: var(--muted); }

  /* ---------- CTA band ---------- */
  .cta-band { background: var(--surface-dark); text-align: center; }
  .cta-band h2 { color: #fff; margin-bottom: 14px; }
  .cta-band p { color: var(--on-dark-soft); margin-bottom: 28px; }

  /* ---------- FAQ ---------- */
  .faq-item { border-bottom: 1px solid var(--hairline); }
  .faq-q { width: 100%; text-align: left; background: none; border: none; padding: 20px 4px; display: flex; align-items: center; justify-content: space-between; font-size: 16px; font-weight: 600; color: var(--ink); }
  .faq-q .icon { transition: transform .2s ease; flex-shrink: 0; }
  .faq-item.open .faq-q .icon { transform: rotate(45deg); }
  .faq-a { max-height: 0; overflow: hidden; transition: max-height .25s ease; }
  .faq-item.open .faq-a { max-height: 240px; }
  .faq-a p { padding: 0 4px 20px; font-size: 15px; color: var(--muted); line-height: 1.6; }

  /* ---------- Footer ---------- */
  footer { background: var(--canvas-parchment); padding: 64px 0 32px; }
  .footer-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; margin-bottom: 40px; }
  .footer-col h4 { font-size: 13px; text-transform: uppercase; letter-spacing: 1px; color: var(--muted-soft); margin-bottom: 16px; }
  .footer-col a { display: block; font-size: 14px; color: var(--muted); padding: 6px 0; }
  .footer-col a:hover { color: var(--primary); }
  .footer-bottom { border-top: 1px solid var(--hairline); padding-top: 24px; text-align: center; }

  /* ---------- Text to PDF ---------- */
  .ttpdf-card { max-width: 780px; margin: 0 auto; background: var(--surface-card); border: 1px solid var(--hairline); border-radius: 18px; padding: 24px; }
  .theme-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-bottom: 16px; }
  .theme-card { border: 1.5px solid var(--hairline); border-radius: 14px; padding: 14px; text-align: left; background: var(--canvas); transition: .15s ease; }
  .theme-card .swatch { width: 100%; height: 8px; border-radius: 9999px; margin-bottom: 12px; }
  .theme-card h4 { font-size: 14px; margin-bottom: 4px; }
  .theme-card p { font-size: 12px; color: var(--muted); line-height: 1.4; }
  .theme-card.selected { border-color: var(--primary); box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 15%, transparent); }

  .mode-toggle { display: flex; gap: 8px; margin-bottom: 16px; }
  .mode-btn { flex: 1; padding: 12px; border-radius: 9999px; border: 1px solid var(--hairline-strong); background: var(--canvas); color: var(--muted); font-size: 14px; font-weight: 600; }
  .mode-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }

  .ttpdf-meta { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 14px; flex-wrap: wrap; }
  .ttpdf-meta .btn { flex-shrink: 0; }
  .usage-badge { display: inline-flex; align-items: center; gap: 6px; }
  .usage-badge.unlocked { color: var(--success); font-weight: 600; }

  /* ---------- Promo modal ---------- */
  .modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.5); z-index: 200; display: flex; align-items: center; justify-content: center; padding: 20px; }
  .modal-card { position: relative; width: 100%; max-width: 400px; background: var(--canvas); border-radius: 18px; padding: 32px 28px; }
  .modal-card h3 { font-size: 20px; margin-bottom: 8px; }
  .modal-card .caption { margin-bottom: 16px; display: block; }
  .modal-close { position: absolute; top: 14px; right: 14px; width: 32px; height: 32px; border-radius: 9999px; border: none; background: var(--surface-strong); color: var(--ink); display: flex; align-items: center; justify-content: center; }

  /* ---------- Loading screen ---------- */
  #loading-screen { position: fixed; inset: 0; background: var(--surface-dark); z-index: 999; display: flex; align-items: center; justify-content: center; transition: opacity .3s ease; }
  #loading-screen svg circle { fill: none; stroke: var(--primary); stroke-width: 3; stroke-linecap: round; stroke-dasharray: 130; stroke-dashoffset: 100; transform-origin: center; animation: loading-rotate 1.1s linear infinite; }
  @keyframes loading-rotate { to { transform: rotate(360deg); } }

  @media (max-width: 900px) {
    .feature-grid { grid-template-columns: repeat(2, 1fr); }
  }
  @media (max-width: 640px) {
    section { padding: 56px 0; }
    .hero-display { font-size: 34px; }
    .display-lg { font-size: 28px; }
    .feature-grid { grid-template-columns: 1fr; }
    .steps { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; gap: 24px; }
    .format-tab span { display: none; }
    .theme-grid { grid-template-columns: 1fr; }
    .ttpdf-meta { flex-direction: column; align-items: stretch; }
    .ttpdf-meta .btn { width: 100%; }
    .generator-actions { flex-direction: column; align-items: stretch; }
    .generator-actions .btn { width: 100%; }
  }