:root {
    --paper: #f7f6f2;
    --surface: #efede6;
    --ink: #14211f;
    --muted: #5a6764;
    --rule: #dcd9cf;
    --accent: #1f6f68;
    --accent-ink: #ffffff;
    --warm: #c8743a;
    color-scheme: light;
  }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
      --paper: #0c1413;
      --surface: #14201e;
      --ink: #e8eeec;
      --muted: #9aa8a5;
      --rule: #23302e;
      --accent: #5cc2b6;
      --accent-ink: #08201d;
      --warm: #e89a62;
      color-scheme: dark;
    }
  }
  :root[data-theme="dark"] {
    --paper: #0c1413; --surface: #14201e; --ink: #e8eeec; --muted: #9aa8a5;
    --rule: #23302e; --accent: #5cc2b6; --accent-ink: #08201d; --warm: #e89a62;
    color-scheme: dark;
  }
  * { box-sizing: border-box; }
  html { -webkit-text-size-adjust: 100%; }
  body {
    margin: 0;
    background: var(--paper);
    color: var(--ink);
    font-family: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", system-ui, sans-serif;
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
  }
  a { color: inherit; }
  .wrap { max-width: 1040px; margin: 0 auto; padding: 0 20px; }
  header.top {
    display: flex; align-items: center; justify-content: space-between;
    padding: 20px 0;
  }
  .brand { display: flex; align-items: center; gap: 10px; font-weight: 700; text-decoration: none; }
  .brand svg { width: 28px; height: 28px; color: var(--accent); }
  .top nav a { color: var(--muted); text-decoration: none; margin-left: 20px; font-size: 15px; }
  .top nav a:hover { color: var(--ink); }

  .hero { padding: 72px 0 88px; display: grid; gap: 48px; grid-template-columns: 1.15fr 0.85fr; align-items: center; }
  .eyebrow { color: var(--accent); font-weight: 500; letter-spacing: .04em; font-size: 15px; margin: 0 0 16px; }
  h1 {
    font-family: "Noto Serif TC", serif; font-weight: 600;
    font-size: clamp(30px, 4.6vw, 50px); line-height: 1.25; margin: 0;
    letter-spacing: -0.01em; text-wrap: balance;
  }
  .nw { white-space: nowrap; }
  .lede { color: var(--muted); font-size: 18px; margin: 24px 0 32px; max-width: 34em; }
  .ctas { display: flex; flex-wrap: wrap; gap: 12px; }
  .btn {
    display: inline-flex; align-items: center; gap: 8px;
    padding: 12px 22px; border-radius: 999px; font-weight: 500; text-decoration: none;
    border: 1px solid var(--rule); transition: transform .15s ease, background .15s ease;
  }
  .btn:active { transform: scale(.97); }
  .btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
  .btn:not(.primary):hover { background: var(--surface); }
  .btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
  .note { font-size: 14px; color: var(--muted); margin-top: 14px; }

  .chat {
    background: var(--surface); border: 1px solid var(--rule); border-radius: 24px;
    padding: 22px; display: flex; flex-direction: column; gap: 12px;
  }
  .chat .meta { font-size: 13px; color: var(--muted); display: flex; align-items: center; gap: 8px; }
  .chat .meta .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--warm); }
  .bubble { padding: 10px 14px; border-radius: 16px; max-width: 88%; font-size: 15px; line-height: 1.6; }
  .bubble.me { align-self: flex-end; background: var(--accent); color: var(--accent-ink); border-bottom-right-radius: 4px; }
  .bubble.ai { align-self: flex-start; background: var(--paper); border: 1px solid var(--rule); border-bottom-left-radius: 4px; }

  section { padding: 72px 0; border-top: 1px solid var(--rule); }
  h2 { font-size: clamp(24px, 3vw, 30px); margin: 0 0 12px; letter-spacing: -0.01em; }
  .sub { color: var(--muted); margin: 0 0 40px; max-width: 36em; }
  .grid3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
  .card { background: var(--surface); border: 1px solid var(--rule); border-radius: 18px; padding: 24px; }
  .card h3 { margin: 12px 0 6px; font-size: 18px; }
  .card p { margin: 0; color: var(--muted); font-size: 15px; }
  .card svg { width: 26px; height: 26px; color: var(--accent); }

  .steps { counter-reset: step; list-style: none; padding: 0; margin: 0; display: grid; gap: 16px; max-width: 680px; }
  .steps li { counter-increment: step; display: grid; grid-template-columns: 40px 1fr; gap: 14px; align-items: start; }
  .steps li::before {
    content: counter(step); width: 32px; height: 32px; border-radius: 50%;
    background: var(--surface); border: 1px solid var(--rule);
    display: grid; place-items: center; font-weight: 700; font-size: 14px; color: var(--accent);
    font-variant-numeric: tabular-nums;
  }
  .steps strong { display: block; }
  .steps span { color: var(--muted); font-size: 15px; }
  code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: .9em; background: var(--surface); border: 1px solid var(--rule); padding: 1px 6px; border-radius: 6px; }

  .two { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
  .bounds { list-style: none; padding: 0; margin: 0; display: grid; gap: 12px; }
  .bounds li { padding-left: 22px; position: relative; color: var(--muted); }
  .bounds li::before { content: ""; position: absolute; left: 0; top: .7em; width: 8px; height: 8px; border-radius: 2px; background: var(--accent); }
  .help { background: var(--surface); border: 1px solid var(--rule); border-left: 4px solid var(--warm); border-radius: 12px; padding: 20px 22px; }
  .help h3 { margin: 0 0 8px; font-size: 17px; }
  .help p { margin: 0 0 6px; color: var(--muted); font-size: 15px; }

  footer { border-top: 1px solid var(--rule); padding: 32px 0 48px; color: var(--muted); font-size: 14px; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; }
  footer a { color: var(--muted); }

  @media (max-width: 820px) {
    .hero { grid-template-columns: 1fr; padding: 40px 0 56px; gap: 36px; }
    .grid3, .two { grid-template-columns: 1fr; }
    section { padding: 56px 0; }
    .top nav a:not(.lang) { display: none; }
  }
  @media (prefers-reduced-motion: reduce) { .btn { transition: none; } }
.top nav a.lang { border: 1px solid var(--rule); border-radius: 999px; padding: 4px 12px; }
.top nav a.lang:hover { background: var(--surface); }