html, body {
 height: 100%; 
 max-width:500px;
 margin-top: 5px;
 margin-right: 5px;
 margin-bottom: 5px;
 margin-left: 5px;
 font-family: "verdana", monospace;
 font-size: 16px; 
  }
  
 .header {
  font-size: 24px; 
  text-align: center
}

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: white;
}

li {
  float: left;
}

li a {
  display: block;
  color: black;
  text-align: center;
  padding: 10px 12px;
  text-decoration: none;
}
li b {
  display: block;
  color: black;
  background-color: grey;
  text-align: center;
  padding: 10px 12px;
  text-decoration: none;
}

li a:hover {
  background-color: grey;
}

.links {
  color: blue;
  font-size: 16px;
  font-weight: normal;
}