.container-div {
    margin: 0 auto;
    width: 100%;
    height: 100%;
    font-size: 28px;
    color: tomato;
    background: url("/static/images/container-bg.jpg");
}
.img {
    width: 100%;
    height: 100%;
}

#back_img{
    width:100%;
    background: url("/static/images/background2.jpeg");
    background-repeat: no-repeat;
    background-size:cover;
    background-attachment:fixed;
    background-position: 50% 50%;
    position:absolute;
    top:0;
    left:0;
    bottom:0;
    right:0;
    z-index:-1
    }
    
#back_img_mobile{
    width:100%;
    background: url("/static/images/background-mobile3.jpeg");
    background-repeat: no-repeat;
    background-size:cover;
    background-attachment:fixed;
    background-position: 50% 50%;
    position:absolute;
    top:0;
    left:0;
    bottom:0;
    right:0;
    z-index:-1
}
.img-responsive{
    display: block;
      width: 100%;
      height: 100%;
}