You can’t just do @media (prefers-reduced-data: no-preference) alone because, as Kilian Valkhof says:
[…] that would be false if either there was no support (since the browser wouldn’t understand the media query) or if it was supported but the user wanted to preserve data.
Usually @supports is the tool for this in CSS, but that doesn’t work with @media queries. Turns out there is a solution though:
@media not all and (prefers-reduced-data), (prefers-reduced-data) {
/* ... */
}This is a somewhat complex logic puzzle involving media query syntax and how browsers evaluate these things. It’s nice you can ultimately handle a no-support fallback situation in one expression.