footer {
    padding:15px;
    background-color:orange;
}
.topnav a {
    padding:16px, 24px;
    float:left;
    color:red;
    text-align:center;
    font-size:17px;
    text-decoration:none;
    display:block;
}
.topnav {
    overflow:hidden;
    background-color:lightgreen;
}
.topnav a:hover {
    background-color:gray;
    color:black;
}
.topnav a.active {
    background-color:red;
    color:white;
}
div {
    padding:16px;
    background-color:lightgray;
}
#answer {
    font-style:italic;
}