body {
     color: white;
     background-color: dimgray;
     }
     
h1{
  position: -webkit-sticky;
  position: sticky;
  top: 0;
  padding: 10px;
  border: 5px solid gray;
  margin: 0;
  color: white;
  background-color: black;
}

ul {
  list-style-type: none;
}

ul li {
  display: block;
  float: center;
  margin: 10px ;
  padding: 10px;
  border: 5px solid gray;
  overflow: hidden;
  color: white;
  background-color: black;
}

ul li a {
  display: block;
  margin: 10px ;
  padding: 10px;
  border: 5px solid gray;
  overflow: hidden;
  color: white;
  background-color: black;
  text-align: center;
}

ul li a:hover {
  background-color: #111111;
}