body{
      background-color: #aaa;
    }
    li{
      font-size: 3em;
    }
a:link {
    background-color: green;
}

a:visited {
    background-color: orange;
}

a:hover {
    background-color: red;
    text-decoration: none;
}

a:active {
    background-color: yellow;
}