:root {
      color-scheme: dark;
      --background: #000;
      --text: #f5f5f7;
      --muted: #a1a1aa;
      --subtle: #81818b;
      --line: #2c2c30;
      --accent: #9bc2f2;
      --gutter: clamp(20px, 5vw, 56px);
    }
    * { box-sizing: border-box; }
    body {
      margin: 0;
      background: var(--background);
      color: var(--text);
      font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC", "Microsoft YaHei", sans-serif;
      font-size: 16px;
      line-height: 1.8;
      -webkit-font-smoothing: antialiased;
      text-rendering: optimizeLegibility;
    }
    a { color: inherit; text-underline-offset: .2em; }
    a:hover { color: var(--accent); }
    :focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
    .site-header {
      position: sticky;
      top: 0;
      z-index: 1;
      border-bottom: 1px solid var(--line);
      background: rgb(0 0 0 / .9);
      backdrop-filter: blur(22px);
      -webkit-backdrop-filter: blur(22px);
    }
    .header-inner, main, .footer-inner {
      width: min(100%, 1200px);
      margin: 0 auto;
      padding-inline: var(--gutter);
    }
    .header-inner {
      display: flex;
      min-height: 68px;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
    }
    .brand { font-size: 19px; font-weight: 700; letter-spacing: -.02em; text-decoration: none; }
    nav { display: flex; align-items: center; gap: clamp(14px, 3vw, 32px); }
    nav a { display: inline-flex; align-items: center; min-height: 44px; color: var(--muted); font-size: 14px; text-decoration: none; white-space: nowrap; }
    nav [aria-current] { color: var(--text); }
    main { padding-top: clamp(56px, 9vw, 108px); padding-bottom: 48px; }
    .reading-column { max-width: 760px; }
    h1 { margin: 0; font-size: clamp(40px, 6vw, 64px); line-height: 1.12; letter-spacing: -.04em; }
    .intro { margin: 24px 0 0; color: var(--muted); font-size: clamp(18px, 2.2vw, 22px); line-height: 1.6; }
    .meta { margin: 16px 0 0; color: var(--subtle); font-size: 14px; }
    .promise { margin-top: 48px; padding: clamp(24px, 4vw, 36px); border: 1px solid #23354d; border-radius: 20px; background: #0c1420; }
    .promise-content { border-left: 3px solid var(--accent); padding-left: 22px; }
    h2 { margin: 0; font-size: clamp(22px, 2.7vw, 26px); line-height: 1.35; letter-spacing: -.02em; }
    .promise p { margin: 12px 0 0; color: #c0cbd9; }
    .sections { margin-top: 56px; }
    .sections section { padding: 30px 0 34px; border-top: 1px solid var(--line); }
    .sections section:first-child { padding-top: 0; border: 0; }
    .sections p { margin: 14px 0 0; color: var(--muted); }
    .sections a { color: var(--accent); }
    footer { margin-top: 32px; border-top: 1px solid var(--line); }
    .footer-inner { display: flex; justify-content: space-between; gap: 20px; padding-block: 28px 40px; color: var(--subtle); font-size: 13px; }
    @media (max-width: 600px) {
      .header-inner { flex-wrap: wrap; gap: 0 16px; padding-block: 10px; }
      .brand { font-size: 17px; }
      nav { gap: 16px; }
      nav a { font-size: 13px; }
      .promise { margin-top: 36px; }
      .promise-content { padding-left: 16px; }
      .sections { margin-top: 40px; }
      .footer-inner { flex-wrap: wrap; gap: 8px 20px; }
    }