I wanted to do flowing content over fixed background. It works perfectly on desktop. On iOS also works but not perfect. Main problem is on android phones. It isn't covering content. If you want edit it, here is CodePen link.
body{
height:200vh;
}
#one{
height:300px;
width:100%;
background:url('https://www.w3schools.com/w3css/img_fjords.jpg') center center no-repeat fixed/cover;
}
#two{
padding-top:30px;
background-color:grey;
height:400px;
padding-left:10px;
}
.column{
width:calc((100% / 3) - 10px);
height:200px;
float:left;
margin-right:10px;
background:url('https://www.w3schools.com/w3css/img_fjords.jpg') center center no-repeat fixed/cover;
}
<body>
<section id="one"></section>
<section id="two">
<div class="column column_one"></div>
<div class="column column_two"></div>
<div class="column column_three"></div>
</section>
</body>