/* 导航栏 */
    .header {
      background-color: transparent;
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      z-index: 100;
      transition: background-color 0.3s ease, padding 0.3s ease;
    }
    .header.scrolled {
      background-color: rgba(255, 255, 255, 0.95);
      box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
      position: sticky;
    }
    .nav {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 18px 0;
    }
    .logo {
      display: flex;
      align-items: center;
    }
    .logo-icon {
      width: 70px;
      height: 50px;
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      margin-right: 12px;
      transition: transform 0.3s ease;
    }
    .logo-text {
      font-size: 20px;
      font-weight: 700;
      color: white;
    }
    .header.scrolled .logo-text {
      color: #165DFF;
    }
    .nav-menu {
      display: flex;
      list-style: none;
    }
    .nav-item {
      margin-left: 35px;
      position: relative;
    }
    .nav-link {
      font-size: 15px;
      color: white;
      font-weight: 500;
      transition: color 0.3s ease;
      padding: 5px 0;
    }
    .header.scrolled .nav-link {
      color: #333;
    }
    .nav-link:hover {
      color: #165DFF;
    }
    .nav-link.active {
      color: #165DFF;
    }
    .nav-link.active::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background-color: #165DFF;
      border-radius: 1px;
    }
    .mobile-menu-btn {
      display: none;
      font-size: 24px;
      color: white;
      cursor: pointer;
    }
    .header.scrolled .mobile-menu-btn {
      color: #333;
    }