I found maybe best solution for parallax effect which work on all devices.
Main thing is to set all sections with z-index greater than parallax section.
And parallax image element to set fixed with max width and height
body, html { margin: 0px; }_x000D_
section {_x000D_
position: relative; /* Important */_x000D_
z-index: 1; /* Important */_x000D_
width: 100%;_x000D_
height: 100px;_x000D_
}_x000D_
_x000D_
section.blue { background-color: blue; }_x000D_
section.red { background-color: red; }_x000D_
_x000D_
section.parallax {_x000D_
z-index: 0; /* Important */_x000D_
}_x000D_
_x000D_
section.parallax .image {_x000D_
position: fixed; /* Important */_x000D_
top: 0; /* Important */_x000D_
left: 0; /* Important */_x000D_
width: 100%; /* Important */_x000D_
height: 100%; /* Important */_x000D_
background-image: url(https://www.w3schools.com/css/img_fjords.jpg);_x000D_
background-repeat: no-repeat;_x000D_
background-position: center;_x000D_
-webkit-background-size: cover;_x000D_
-moz-background-size: cover;_x000D_
-o-background-size: cover;_x000D_
background-size: cover;_x000D_
}
_x000D_
<section class="blue"></section>_x000D_
<section class="parallax">_x000D_
<div class="image"></div>_x000D_
</section>_x000D_
<section class="red"></section>
_x000D_