.header {
    background-color: #F1F1F1;
    text-align: center;
    padding: 20px;
}

.topnav {
    overflow: hidden;
    background-color: #ffcaca;
}
.topnav a {
    float: left;
    display: block;
    color: black;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
    background-color: #ffcaca;
}
.topnav a:hover {
    background-color: #ffcaca;
    color: blue;
}


.column {
    float: left;
    width: 100%;
}
.row:after {
    content: "";
    display: table;
    clear: both;
}

.footer {
    background-color: #F1F1F1;
    text-align: center;
    padding: 10px;
}