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@media.prefers-reduced-data

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

Draft
This page is not complete.

Note: This feature is not supported by any user agent and its specifics are subject to change.

The prefers-reduced-data CSS media feature is used to detect if the user has requested the web content that consumes less internet traffic.

Syntax

no-preference: Indicates that the user has made no preference known to the system. This keyword value evaluates as false in the boolean context.
reduce: Indicates that user has expressed the preference for lightweight alternate content.

User preferences

Currently no user agent implements this feature, although various operating systems do support such preferences and if this media query is ever implemented user agents will likely rely on the settings provided by the operating system.

Examples

Note: No browser currently implements this feature so the following example will not work.

In this example the montserrat-regular.woff2 font file will neither be preloaded nor downloaded if the user prefers reduced data, in this case the "system font stack" will serve as the fallback font:

HTML

<head>
  <link rel="preload" href="fonts/montserrat-regular.woff2" as="font" media="(prefers-reduced-data: no-preference)" crossorigin>
  <link rel="stylesheet" href="style.css">
</head>

CSS

@media (prefers-reduced-data: no-preference) {
    @font-face {
        font-family: Montserrat;
        font-style: normal;
        font-weight: 400;
        font-display: swap;
        /* latin */
        src: local('Montserrat Regular'), local('Montserrat-Regular'), url('fonts/montserrat-regular.woff2') format('woff2');
        unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
    }
}

body {
  font-family: Montserrat, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, "Microsoft YaHei", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}

Result

Specifications

Specification	Status	Comment
Media Queries Level 5 The definition of 'reduced-data' in that specification.	Editor's Draft	Initial definition.

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
`prefers-reduced-data` media feature	85 Disabled 85 Disabled See bug 1051189. Disabled From version 85: this feature is behind the `#enable-experimental-web-platform-features` preference (needs to be set to `Enabled`). To change preferences in Chrome, visit chrome://flags.	85 Disabled 85 Disabled See bug 1051189. Disabled From version 85: this feature is behind the `#enable-experimental-web-platform-features` preference (needs to be set to `Enabled`).	No	No	No	No

	Mobile
	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`prefers-reduced-data` media feature	No No See bug 1051189.	85 Disabled 85 Disabled See bug 1051189. Disabled From version 85: this feature is behind the `#enable-experimental-web-platform-features` preference (needs to be set to `Enabled`). To change preferences in Chrome, visit chrome://flags.	No	No	No	No