.def_footer {
    background-color: #181818;
    color: #FFFFFF;
    text-align: center;
    padding: 20px;
    font-size: 16px;
    z-index: 10;
}

@media (max-width: 768px) {
    .def_footer {
        background-color: #181818;
        color: #FFFFFF;
        text-align: center;
        padding: 20px;
        font-size: 3.5vw;
        max-width: 100%;
        padding: 4vw 3vw;
        width: auto;
    }
}