.sidenav {
  position: sticky;
  height: 100%; 
  width: 20vw; 
  top: 200px; 
  background-color: #111;
  overflow-x: hidden;
  padding-top: 40px;
  transition: 0.5s;
  z-index: 1;
}

.sidenav a {
  padding: 8px 8px 8px 32px;
  text-decoration: none;
  font-size: 16px;
  color: #818181;
  display: block;
  transition: 0.3s;
}

.sidenav a:hover {
  color: #f1f1f1;
}

.maindiv {
    width: 95vw;
    transform: translateY(-30%);
    z-index:0;
}