body{
    background-color: yellow;
    font-family: sans-serif;
    text-align: center;
    cursor: default;
}

a{
  text-decoration: none;
  border: 1px solid black;
  color: black;
  cursor: cell;
}
a:hover{
  text-decoration: underline;
  border: 3px solid white;
  color: white;
  background-color: black;
}

h1{
    border-bottom: 3px solid black;
}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
    border-radius: 10px;
  }
  
  li {
    float: left;
  }
  
  li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
  }
  
  li a:hover {
    background-color: #111;
  }