You set an image to fullscreen in your site, and on PC it works great, but on mobile it fucking moves when scrolling… That's because you need to change background-attachment: “fixed” to “scroll” on your mobile media queries.
Example:
main { background: url(/img/background.jpg); background-repeat: no-repeat; background-size: cover; background-position: center; background-attachment: fixed; overflow: auto; height: 100%; } @media (max-width: 400px) { main { background-attachment: scroll; } }