.parallax-img-300 {background-attachment: fixed; margin-top: -30px;}
@media only screen and (max-width:767px){
 .class-name{margin-top: -20px;}
}
.parallax-img-300 .block-bg-img {padding: 100px 100px 300px 100px;}
.bg-img-300 .block-bg-img {padding: 100px 100px 300px 100px;}