footer{
    position: relative;
    background-image:url('../img/bg_rodape.jpg'); 
    background-size: cover;    
    background-position: center center;    
    background-repeat: no-repeat;   
    background-color: #181818;
}

footer::before{    
    content: "";
    display: block;
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    background-color: rgba(0, 0, 0, 0.8);
}