background attachment fixed in IOS mobile
body:before {
content: "";
display: block;
position: fixed;
left: 0;
top: 0;
width: 100%;
height: 100%;
z-index: -10;
background: url(photos/test.jpg) no-repeat center center;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}