.topbar {
  text-align: center;
  left: 0; 
  top: 0; 
  width: 100%; 
  z-index: -1; 
  background-color: grey;
}

.contentdiv {
  background-color: white;
  width: 80%;
  left: 0;
  top: 50;
  float: left;
}

.sidebar {
  margin-left: 80%;
  width: 20%;
  right: 0;
  top: 50;
}