#navbar {
    float: left;
    width: 30%;
    height: 100%;
    position: fixed;
    overflow-y: scroll;
    border: outset;
    text-align: center;
    line-height: 170%;
    text-decoration: none;
  }
  
  .nav-link {
    text-decoration: none;
  }
  
  #main-doc {
    float: right;
    width: 65%;
  }
  
  .block {
    background: lightgray;
    text-align: center;
    padding: 20px;
    margin: 20px;
  }
  
  header {
    font-weight: bold;
    font-size: 30px;
  }
  
  @media (max-width: 760px) {
  #navbar {
    float: none;
    position: relative;
    width: 100%;
    height: 30%;
  }
  
  #main-doc {
    float: none;
  }
  }