body {
  margin: 0;
  font-family: 'Fira Sans', Arial, Helvetica, sans-serif;
}
      
.header {
  background-color: #f1f1f1;
  padding: 30px;
  text-align: center;
}
      
#navbar {
  position: sticky;
  top: 0;
  overflow: hidden;
  background-color: #333;
}
    
#navbar a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

#navbar a:hover {
  background-color: #ddd;
  color: black;
}

#navbar active {
  background-color: #04AA6D;
  color: white;
}

.content {
  padding: 16px;
}

.footer {
  font-style: italic;
  font-size: 80%;
  text-align: center;
}