I'm trying to use background-attachment: fixed. On desktop, this works as expected. But on mobile, it's broken. The background image moves with the page.

I've read workarounds that include using position: fixed, but if it's disabled on mobile, there must be a reason for it.

Here's an example of a page that uses the parallax scrolling effect: https://www.w3schools.com/howto/tryhow_css_parallax_demo.htm