/* Remove this if you dont want background overlay over the image or adjust per your needs */
body.login_admin:before {
    content: " ";
    background: rgba(0, 0, 0);
    min-height: 100%;
    min-width: 100%;
    position: absolute;
}
body.customers_login:before {
    content: " ";
    background: rgba(0, 0, 0);
    min-height: 100%;
    min-width: 100%;
    position: absolute;
}