.site-header {
      background: var(--bg);
      position: sticky; top: 0; z-index: 100;
      padding: 0 24px;
      display: flex; justify-content: center;
    }
    .nav-container {
      display: flex; gap: 8px; height: 56px; align-items: center; justify-content: center;
      max-width: 1200px; width: 100%;
    }
    /* 左侧官网入口 */
    .nav-home-btn {
      color: var(--text); font-weight: 500; font-size: 14px;
      text-decoration: none; padding: 8px 16px; border-radius: 8px;
      transition: all 0.2s; white-space: nowrap;
      margin-right: 8px;
    }
    .nav-home-btn:hover { color: var(--text); background: var(--bg2); }
    /* 右侧 APP 下载按钮 */
    .nav-app-btn {
      color: var(--accent); font-weight: 600; font-size: 13px;
      text-decoration: none; padding: 8px 16px; border-radius: 8px;
      border: 1px solid rgba(88,166,255,0.35);
      background: rgba(88,166,255,0.08);
      transition: all 0.2s; white-space: nowrap;
      margin-left: 8px;
    }
    .nav-app-btn:hover { background: rgba(88,166,255,0.18); border-color: var(--accent); }
    /* 语言切换下拉 */
    .nav-lang-dd { position: relative; }
    .lang-menu {
      position: absolute; top: calc(100% + 4px); right: 0;
      background: var(--bg2); border: 1px solid var(--border);
      border-radius: 10px; padding: 6px; min-width: 140px;
      box-shadow: 0 8px 24px rgba(0,0,0,0.3);
      display: none; flex-direction: column; gap: 2px; z-index: 300;
    }
    .nav-lang-dd:hover .lang-menu { display: flex; }
    .lang-opt {
      display: flex; align-items: center; gap: 8px;
      background: none; border: none; padding: 8px 12px;
      border-radius: 7px; color: var(--text2); font-size: 14px;
      cursor: pointer; font-family: inherit; width: 100%;
      text-align: left; transition: all .15s;
    }
    .lang-opt:hover { background: var(--bg3); color: var(--text); }
    .lang-opt.active { color: var(--accent); }
    .nav-dropdown {
      height: 100%; display: flex; align-items: center;
    }
    .nav-container > a, .nav-dropdown > a, .nav-dropdown > button {
      color: var(--text3); font-weight: 500; font-size: 14px;
      text-decoration: none; padding: 8px 16px; border-radius: 8px;
      border: 0; background: transparent; font-family: inherit;
      transition: all 0.2s; cursor: pointer; display: flex; align-items: center; gap: 6px;
    }
    .nav-container > a:hover, .nav-dropdown:hover > a, .nav-dropdown:hover > button { color: var(--text); background: var(--bg2); }
    .nav-container > a.nav-app-btn { color: var(--accent); }
    .nav-container > a[data-active="true"], .nav-dropdown > a[data-active="true"] {
      color: var(--text); background: var(--bg3);
    }
    .chevron { font-size: 12px; transition: transform 0.2s; opacity: 0.6; }
    .nav-dropdown:hover .chevron { transform: rotate(180deg); }

    /* Mega Menu */
    .mega-menu {
      position: absolute; top: 100%; left: 0; right: 0;
      background: var(--bg); border-bottom: 1px solid var(--border);
      box-shadow: 0 10px 30px rgba(0,0,0,0.3);
      display: none; z-index: 200; padding: 24px 0;
    }
    .nav-dropdown:hover .mega-menu { display: block; }
    .mega-menu-inner {
      max-width: 1200px; margin: 0 auto; padding: 0 24px;
      display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px;
    }

    /* Mega Card */
    .mega-card {
      display: flex; align-items: flex-start; gap: 16px;
      padding: 16px; border-radius: 12px; text-decoration: none !important;
      background: transparent; border: 1px solid transparent;
      transition: all 0.2s;
    }
    .mega-card:hover {
      background: var(--bg2); border-color: var(--border);
    }
    .mega-card[data-active="true"] {
      background: rgba(88,166,255,0.08); border-color: rgba(88,166,255,0.3);
    }
    .mega-card-icon {
      font-size: 20px; line-height: 1; filter: grayscale(1) opacity(0.7); transition: all 0.2s;
    }
    .mega-card:hover .mega-card-icon, .mega-card[data-active="true"] .mega-card-icon {
      filter: grayscale(0) opacity(1);
    }
    .mega-card-content { display: flex; flex-direction: column; gap: 4px; }
    .mega-card-title { color: var(--text); font-weight: 500; font-size: 15px; transition: color 0.2s; }
    .mega-card[data-active="true"] .mega-card-title { color: var(--accent); }
    .mega-card-desc { color: var(--text3); font-size: 13px; line-height: 1.4; }

    /* Agent has two peer destinations on every PC page. */
    .nav-agent-dd .agent-menu-inner { grid-template-columns: repeat(2, minmax(230px, 1fr)); max-width: 760px; }
    .nav-agent-dd .mega-card { border-radius: 8px; }
    .nav-agent-dd:focus-within .mega-menu { display: block; }
    @media (max-width: 1000px) {
      .nav-agent-dd .agent-menu-inner { grid-template-columns: repeat(2, minmax(180px, 1fr)); }
    }