.container {
      height: 200px;
      position: relative;
      border: 3px solid green;
    }
    
    /* Add a black background color to the top navigation */
    .topnav {
      background-color: #333;
      overflow: hidden;
    }
    
    /* Style the links inside the navigation bar */
    .topnav a {
      float: left;
      color: #f2f2f2;
      text-align: center;
      padding: 14px 16px;
      text-decoration: none;
      font-size: 17px;
    }
    
    /* Change the color of links on hover */
    .topnav a:hover {
      background-color: #ddd;
      color: black;
    }
    
    /* Add a color to the active/current link */
    .active {
      background-color: #55acee;
      color: white;
    }
    
    
    .vertical-center {
      margin: 0;
      position: absolute;
      left: 50%;
      transform: translateX(-50%);
    }
    
        h1 {
            color: green;
        }