#footer {
    position: fixed;
    text-align: center;
    width: 100%;
    bottom: 0;
    height: 40px;
    margin: 0;
    padding: 10px;
}

body::after {
    content: '';
    display: block;
    height: 40px; /* Set same as footer's height */
}

div#main {
    background-color: transparent;
}