body {
      font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
      background-color: #f9fafb;
      color: #333;
  }

  /* 导航栏样式 */
  .nav-item {
      position: relative;
  }

  .dropdown-menu {
      display: none;
      position: absolute;
      top: 100%;
      left: 0;
      background-color: white;
      box-shadow: 0 10px 25px rgba(37, 99, 235, 0.15);
      min-width: 200px;
      z-index: 50;
      border-top: 3px solid #2563eb;
      opacity: 0;
      transform: translateY(10px);
      transition: all 0.3s ease;
  }

  .nav-item:hover .dropdown-menu {
      display: block;
      opacity: 1;
      transform: translateY(0);
  }

  .dropdown-item {
      display: block;
      padding: 12px 20px;
      color: #4b5563;
      text-decoration: none;
      border-bottom: 1px solid #f3f4f6;
      transition: all 0.2s;
      font-size: 0.95rem;
  }

  .dropdown-item:hover {
      background-color: #eff6ff;
      color: #2563eb;
      padding-left: 25px;
  }

  /* 时间轴样式 */
  .timeline-item {
      position: relative;
      padding-left: 2rem;
  }

  .timeline-item::before {
      content: '';
      position: absolute;
      left: 0;
      top: 0;
      bottom: 0;
      width: 2px;
      background: #e5e7eb;
  }

  .timeline-item:last-child::before {
      bottom: auto;
      height: 20px;
  }

  .timeline-dot {
      position: absolute;
      left: -6px;
      top: 0;
      width: 14px;
      height: 14px;
      border-radius: 50%;
      background: white;
      border: 3px solid #2563eb;
      z-index: 10;
  }

  .timeline-item:hover .timeline-dot {
      background: #2563eb;
      transform: scale(1.2);
      transition: all 0.3s;
  }

  /* 移动端适配 */
  .mobile-menu-btn {
      display: none;
  }

  @media (max-width: 768px) {
      .mobile-menu-btn {
          display: block;
      }

      .desktop-menu {
          display: none;
      }

      .about-grid {
          grid-template-columns: 1fr;
      }
  }