body {
    margin: 0;
    background-image: url("../img/index-bg.png");
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}
@media screen and (max-width:767px) {
    body {
        background-position: -99999px -99999px;
    }
    body:before {
    	content: "";
    	background-image: inherit;
    	position: fixed;
        background-position: center;
        background-repeat: no-repeat;
    	top: 0;
    	left: 0;
    	height: 100vh;
    	width: 100%;
    	-webkit-background-size: cover !important;
    	-moz-background-size: cover !important;
    	-o-background-size: cover;
    	background-size: cover !important;
    	z-index: -1;
    }
}