They’ve been proposed!: https://drafts.csswg.org/mediaqueries-5/#prefers-reduced-data https://drafts.csswg.org/mediaqueries-5/#prefers-reduced-dat... You can a

They’ve been proposed!: https://drafts.csswg.org/mediaqueries-5/#prefers-reduced-data https://drafts.csswg.org/mediaqueries-5/#prefers-reduced-dat... You can already do this with JavaScript now: https://developer.mozilla.org/en-US/docs/Web/API/NetworkInformation https://developer.mozilla.org/en-US/docs/Web/API/NetworkInfo... though as you can see from the bottom of that link, Browser support is limited at the moment (and experimental so may even be removed/changed!).