nav {
    background-color: #333;
    overflow: hidden;
}

nav a {
    text-decoration: none;
    padding: 20px;
    text-align: center;
    float: left;
    color: white;
}
h1 {
    padding: 20px;
    text-align: center;
    font-size: 40px;
    border: 2px solid black;
    background-color: aquamarine;
}
.a:hover{
    background-color: blue;
}
footer {
    background-color: #333;
    overflow: hidden;
}

footer a {
    text-decoration: none;
    padding: 20px;
    text-align: center;
    float: left;
    color: white;
}
ol{
    background-color: azure;
    margin-bottom: 5px;
}
ul{
    background-color: antiquewhite;
}