/* 顶部导航栏 */
    .header-nav {
      width: 100%;
      height: 70px;
      background: #fff;
      box-shadow: 0 1px 5px rgba(0,0,0,0.1);
      position: fixed;
      top: 0;
      left: 0;
      z-index: 9999;
    }
    .nav-container {
      width: 1200px;
      height: 100%;
      margin: 0 auto;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .logo {
      font-size: 24px;
      font-weight: bold;
      color: #000;
    }
    .nav-list {
      display: flex;
      height: 100%;
    }
    .nav-list > li {
      height: 100%;
      padding: 0 18px;
      display: flex;
      align-items: center;
      cursor: pointer;
      position: relative;
    }
    .nav-list > li > a {
      color: #333;
      font-size: 15px;
      font-weight: 500;
    }
    .nav-list > li:hover > a {
      color: #1428a0;
    }

    /* 全屏下拉菜单容器 */
    .fullscreen-menu {
      position: fixed;
      top: 70px;
      left: 0;
      width: 100%;
      background: #fff;
      box-shadow: 0 4px 10px rgba(0,0,0,0.08);
      z-index: 9998;
      display: none;
      padding: 40px 0;
    }
    .menu-inner {
      width: 1200px;
      margin: 0 auto;
      display: grid;
      grid-template-columns: repeat(5, 1fr);
      gap: 20px;
    }
    .menu-col h3 {
      font-size: 16px;
      color: #000;
      margin-bottom: 15px;
      font-weight: 600;
    }
    .menu-col ul li {
      margin-bottom: 12px;
    }
    .menu-col ul li a {
      font-size: 14px;
      color: #666;
    }
    .menu-col ul li a:hover {
      color: #1428a0;
    }

    /* 遮罩层 */
    .menu-mask {
      position: fixed;
      top: 70px;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(0,0,0,0.3);
      z-index: 9997;
      display: none;
    }

    /* 移动端汉堡菜单 简单适配 */
    .menu-btn {
      display: none;
      font-size: 24px;
      cursor: pointer;
    }

    @media (max-width: 768px) {
      .nav-list {
        display: none;
      }
      .menu-btn {
        display: block;
      }
      .nav-container {
        width: 90%;
      }
      .menu-inner {
        width: 90%;
        grid-template-columns: repeat(2, 1fr);
      }
    }