body {
  font-family: Trebuchet MS;
}

.topnav {
  top: 0;
  font-family: Trebuchet MS;
  margin: 0px;
  overflow: hidden;
  background-color: lightgray;
  width: 100%;
}

.topnav a {
  float: left;
  color: #f2f2f2;
  text-align: center;
  padding: 20px 25px;
  text-decoration: none;
  font-size: 17px;
}
  
.topnav a:hover {
  background-color: lightgray;
  color: black;
}
  
.topnav a.active {
  background-color: lightblue;
  color: white;
}