  <style type="text/css">
     .center, body, #container {
        text-align: left;
        margin-left: auto;
        margin-right: auto;
     }
     #container {
        width: 90%;
     }
     #sidebar {
        float: left;
        width: 10%;
        background-color: rgb(204,204,204);
        font-family: Arial,Helvetica, sans-serif;
        font-size: 15px;
     }
     #content {
        float: right;
        width: 90%;
     }
.vertical-menu {
  width: 100%;
}

.vertical-menu a {
  background-color: #eee;
  color: black;
  display: block;
  padding: 8px;
  text-decoration: none;
  font-size: 12px;
}

.vertical-menu a:hover {
  background-color: #ccc;
}

.vertical-menu a.active {
  background-color: #4CAF50;
  color: white;
}
  </style>

