/* CSS */


*{
    box-sizing: border-box;
  }
  
  body {
    font-family: Arial, Helvetica, sans-serif;
  }
  
  header {
    background-color: #666;
    padding: 3px;
    text-align: center;
    font-size: 20px;
    color: white;
  }
  
  nav {
    float: left;
    width: 18%;
    padding: 20px;
    height: 730px;
    background-color: #444;
    align-content: center;
  }
  
  nav ul {
    list-style-type: none;
    align-content: center;
    align-items: center;
  }
  
  article {
    float: right;
    padding: 20px;
    width: 70%;
    background-color: #f1f1f1;
  
  }
  
  section::after {
    content: "";
    display: table;
    clear: both;
  }
  
  .content {
    background-color: #999;
    padding: 10px;
    text-align: center;
    height: 730px;
    color: black;
  }
  .button {
    background-color: #4CAF50; 
    border: none;
    color: white;
    height: 30px;
    width: 120px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 16px;
    margin: 6px 4px;
    cursor: pointer;
    -webkit-transition-duration: 0.4s; 
    transition-duration: 0.4s;
  }
  .button1:hover {
    box-shadow: 0 12px 16px 0 rgba(0,0,0,0.24),0 17px 50px 0 rgba(0,0,0,0.19);
  }
  
  @media (max-width: 600px) {
    nav, article {
      width: 100%;
      height: auto;
    }
  }