body {
    background-color: lightblue;    
}

h1 {
    color: ghostwhite;
    margin-left: 40px;
}

ul {
    list-style-type: none;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
}

ul > li {
    margin: 30px;
}

ul>li>a {
    background-color: lightgray;
    color: black;
    padding: 20px;
    text-decoration: none;
    border-radius: 10px;
}

ul>li>a:visited {
    background-color: lightgreen;
    color: black;
    padding: 20px;
    text-decoration: none;
    border-radius: 10px;
}