#whats {
    display: inline-block;
    position: fixed;
    width: 63px;
    height: 64px;
    right: 25px;
    bottom: 25px;
    z-index: 1030;
}

#whats img,
#whats a {
    width: 63px;
    height: 64px;
    display: block;
}

@media (max-width: 767px) {
    #whats {
        width: 43px;
        height: 44px;
        right: 15px;
        bottom: 15px;
    }

    #whats img,
    #whats a {
        width: 43px;
        height: 44px;
    }
}