/* navbar */
 body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
}
  
.topnav {
    overflow: hidden;
    background-color: #333;
}
  
.topnav a {
    float: left;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    font-size: 17px;
}
  
.topnav a:hover {
    background-color: #ddd;
    color: black;
}
  
.topnav a.active {
    background-color: #4CAF50;
    color: white;
}