:root {
      --bg: #F6F3EE;
      --card: #FFFCF8;
      --card-warm: #F3EEE6;
      --layer: #EFEBE4;
      --ink: #1C1917;
      --muted: #57534E;
      --accent: #1F4A4E;
      --bronze: #8C6A3D;
      --line: #A8A29A;
      --max: 1120px;
      --header-h: 64px;
      --font-sans: "R37LocalSans", "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", "WenQuanYi Micro Hei", system-ui, -apple-system, sans-serif;
      --font-serif: "R37LocalSerif", "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", "Noto Serif CJK SC", serif;
    }
    * { box-sizing: border-box; }
    html {
      scroll-behavior: smooth;
      scroll-padding-top: calc(var(--header-h) + 16px);
    }
    @media (prefers-reduced-motion: reduce) {
      html { scroll-behavior: auto; }
      *, *::before, *::after { animation: none !important; transition: none !important; }
    }
    body {
      margin: 0;
      background: var(--bg);
      color: var(--ink);
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.75;
    }
    a { color: var(--accent); }
    img { max-width: 100%; height: auto; display: block; }
    h1, h2, h3, h4, p, li, .num, .num-label, .cta, .cta-note {
      overflow-wrap: anywhere;
      word-break: break-word;
    }
    .skip {
      position: absolute; left: -999px; top: 0;
      background: var(--accent); color: var(--bg); padding: 8px 12px; z-index: 100;
    }
    .skip:focus { left: 8px; top: 8px; }
    .proto-banner {
      background: var(--accent);
      color: var(--bg);
      text-align: center;
      font-size: 14px;
      font-weight: 600;
      letter-spacing: 0.02em;
      padding: 10px 16px;
    }
    header.site {
      position: sticky; top: 0; z-index: 40;
      background: rgba(246,243,238,0.96);
      border-bottom: 1px solid #E7E2DA;
    }
    .header-inner, .wrap {
      width: min(var(--max), calc(100% - 40px));
      margin: 0 auto;
    }
    .header-inner {
      min-height: var(--header-h);
      display: flex; align-items: center; justify-content: space-between; gap: 16px;
    }
    .logo {
      font-family: var(--font-serif);
      font-weight: 700; font-size: 20px; line-height: 1.2; color: var(--ink); text-decoration: none;
    }
    nav.desktop { display: none; gap: 18px; align-items: center; flex-wrap: wrap; }
    nav.desktop a {
      color: var(--ink); text-decoration: none; font-size: 14px; padding: 8px 0;
      border-bottom: 2px solid transparent;
    }
    nav.desktop a:hover, nav.desktop a[aria-current] { color: var(--accent); border-bottom-color: var(--accent); }
    nav.desktop a.talk-link { color: var(--accent); font-weight: 600; }
    .nav-toggle {
      appearance: none; border: 1px solid var(--line); background: var(--card);
      color: var(--ink); border-radius: 8px; padding: 8px 12px; min-height: 44px; min-width: 44px;
      font: inherit; font-size: 14px;
    }
    nav.mobile {
      display: none; border-top: 1px solid #E7E2DA; background: var(--bg);
    }
    nav.mobile.open { display: block; }
    nav.mobile a {
      display: block; padding: 12px 20px; color: var(--ink); text-decoration: none;
      border-bottom: 1px solid #E7E2DA;
    }
    nav.mobile a.talk-link { color: var(--accent); font-weight: 600; }
    main { padding-bottom: 40px; }
    section { padding: 56px 0; }
    section[id], #about-model-2, #case-1, #case-2, #top, #main, #talk-cta {
      scroll-margin-top: calc(var(--header-h) + 16px);
    }
    .sec-title {
      font-family: var(--font-serif);
      font-size: 22px; line-height: 1.35; margin: 0 0 28px; font-weight: 700;
    }
    .lead { margin: 0 0 1em; }
    .num {
      font-family: var(--font-serif);
      color: var(--bronze); font-weight: 700; font-size: 36px; line-height: 1.25;
      display: block; margin-bottom: 8px;
    }
    .num-label {
      margin: 0;
      font-size: 15px;
      line-height: 1.5;
      color: var(--ink);
    }
    .num-row { display: grid; gap: 16px; margin: 0 0 28px; }
    .num-card, .layer, .thing, .dir, .ai-card, .course {
      background: var(--card); border: 1px solid #E7E2DA; border-radius: 12px; padding: 20px 24px;
    }
    .num-card { margin: 0; }
    .layer { border-left: 3px solid var(--accent); }
    .layer h3, .thing h3, .dir h3, .ai-card h3 {
      margin: 0 0 10px; font-size: 17px; font-weight: 650; line-height: 1.4;
    }
    .hint, .disclaimer {
      background: var(--layer);
      border-left: 3px solid var(--line);
      padding: 16px 18px;
      margin: 16px 0;
      color: var(--ink);
      font-size: 16px;
    }
    .disclaimer { border-left-color: var(--bronze); }
    .list { margin: 0; padding-left: 1.2em; }
    .quote { margin: 24px 0 0; color: var(--ink); }
    #hero { padding-top: 40px; padding-bottom: 48px; }
    .hero-grid { display: grid; gap: 24px; }
    .brand { margin: 0 0 24px; line-height: 1.25; }
    .brand .name {
      display: block;
      font-family: var(--font-serif);
      font-weight: 700; font-size: 42px; letter-spacing: 0.04em;
    }
    .brand .role {
      display: block; margin-top: 8px;
      font-family: var(--font-serif);
      font-weight: 600; font-size: 18px; color: var(--accent);
    }
    .brand .sr-only-join { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }
    .hero p { font-size: 17px; margin: 0 0 1em; max-width: 40em; }
    .things, .dirs, .ai-grid { display: grid; gap: 16px; }
    .case { margin-bottom: 28px; padding: 24px; border-radius: 12px; border: 1px solid #E7E2DA; }
    .case h3 { margin: 0 0 8px; font-size: 18px; line-height: 1.4; }
    .case-industry { background: var(--card); box-shadow: inset 3px 0 0 var(--accent); }
    .case-retail { background: var(--card-warm); box-shadow: inset 3px 0 0 var(--bronze); }
    .case h4 { margin: 20px 0 8px; font-size: 16px; color: var(--accent); font-weight: 650; }
    .case h4 + p, .case p { margin: 0 0 0.8em; }
    .flow {
      margin: 20px 0 0; padding: 0; list-style: none; display: grid; gap: 8px;
    }
    .flow li {
      background: var(--bg); border: 1px solid #E7E2DA; border-radius: 10px; padding: 12px 14px;
    }
    .flow .step-n { color: var(--accent); font-weight: 650; margin-right: 6px; }
    .flow-note { margin-top: 12px; }
    .cta-area { margin: 28px 0 0; }
    .cta {
      display: flex; align-items: center; justify-content: center;
      background: var(--accent); color: var(--bg);
      font-weight: 600; font-size: 18px; line-height: 1.4;
      min-height: 48px; padding: 12px 24px; border-radius: 10px;
      width: 100%; text-align: center; margin: 0;
    }
    .cta-note {
      margin: 10px 0 0;
      font-size: 14px;
      line-height: 1.5;
      color: var(--muted);
    }
    footer.site { border-top: 1px solid #E7E2DA; padding: 24px 0 32px; color: var(--muted); font-size: 14px; }
    .backtop {
      position: fixed; z-index: 30;
      right: 16px; bottom: 24px;
      width: 44px; height: 44px; border-radius: 22px;
      border: 1px solid var(--line); background: var(--card); color: var(--ink);
      font-size: 12px; display: none; align-items: center; justify-content: center;
      text-decoration: none;
    }
    .backtop.show { display: flex; }
    /* 本轮口径：暂不增加手机底部固定合作按钮，不写入对应元素。 */
    @media (min-width: 768px) {
      .num { font-size: 40px; }
      .num-row { grid-template-columns: 1fr 1fr; }
      .things { grid-template-columns: 1fr 1fr 1fr; }
      .ai-grid { grid-template-columns: 1fr 1fr; }
      .dirs { grid-template-columns: 1fr 1fr; }
      .brand .name { font-size: 56px; }
      .brand .role { font-size: 22px; }
      section { padding: 80px 0; }
      .sec-title { font-size: 26px; }
    }
    @media (min-width: 1024px) {
      nav.desktop { display: flex; }
      .nav-toggle { display: none; }
      nav.mobile, nav.mobile.open { display: none !important; }
      main { padding-bottom: 40px; }
      .backtop { bottom: 24px; }
      .brand .name { font-size: 68px; }
      .hero-grid { grid-template-columns: 1fr; }
      .dirs { grid-template-columns: 1fr 1fr 1fr 1fr; }
      .num { font-size: 48px; }
      .cta { width: auto; max-width: 32em; }
      body { font-size: 17px; }
    }

/* Local enhancement only: keep R37 layout and words. */
nav.mobile { max-height: var(--menu-available, calc(100dvh - var(--header-h) - 56px)); overflow-y: auto; overscroll-behavior: contain; }
.no-js .nav-toggle { display: none; }
.no-js nav.mobile { display: block; max-height: none; }
.no-js header.site { position: static; }

/* R04: supplied contacts only; QR original pixels remain unchanged. */
.contact-grid { display: grid; gap: 28px; margin-top: 24px; padding: 24px; background: var(--card); border: 1px solid var(--line); border-radius: 12px; }
.contact-grid h3 { margin: 0 0 14px; font-size: 18px; }
.wechat-qr { display: block; position: relative; width: min(248px, 100%); aspect-ratio: 1; overflow: hidden; background: #fff; }
.wechat-qr img { position: absolute; width: 180%; max-width: none; height: auto; left: -40%; top: -117.142857%; }
.contact-original { display: inline-flex; align-items: center; min-height: 44px; }
.contact-details p { margin: 0 0 8px; }
.contact-details a { display: inline-flex; align-items: center; min-height: 44px; max-width: 100%; overflow-wrap: anywhere; }
.contact-label { display: block; color: var(--muted); font-size: 14px; }
@media (min-width: 768px) { .contact-grid { grid-template-columns: 1fr 1fr; align-items: start; } }