.nav-container {
      position: fixed;
      top: 0;
      left: 0;
      z-index: 9999;
    }

    .nav-toggle {
      position: absolute;
      top: 0;
      left: 0;
      width: 39px;
      height: 39px;
      border-radius: 50%;
      background-color: transparent;
      cursor: pointer;
      outline: none;
    }

    .nav-list {
      display: none;
      position: absolute;
      top: 50px;   
      left: 0;    
      width: 166px;
      padding: 10px;
      border-radius: 5px;
      background-color: rgba(0, 0, 0, 0.5);
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3);
    }


    .nav-list.show {
      display: block;
    }


    .nav-list li {
      margin-bottom: 10px;
    }

    .nav-list li a {
      display: block;
      color: #fff;
      text-decoration: none;
      font-size: 1px;
    }

    /* 显示导航列表 */
    .nav-list.show {
      display: block;
    }

    .nav-toggle.active {
      background-color:rgba(240, 240, 240, 0.8);
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3);
    }

    .nav-toggle.active:before {
     content: "-";
     color: black;
     text-shadow: none;
    }

    

     .nav-toggle:before {
      content: "+";
      display: block;
      color: white;
      font-size: 30px;
      line-height:36px;
      text-align: center;
    } 


    .nav-toggle.active:hover {
      background-color: transparent;
       outline: none;
    }

    .nav-toggle.active:hover:before {
      color: #fff; 
    }

     .nav-toggle:focus {
     outline: none;
    }