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  6. prefers-reduced-data

prefers-reduced-data CSS media feature

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Want more support for this feature? Tell us why.

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

Warning: 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 web content that consumes less internet traffic.

The browser typically achieves this by querying the underlying operating system's preferences for reduced data.

Syntax

no-preference

Indicates that the user has made no preference known to the system. This keyword evaluates to false in the Boolean context.

reduce

Indicates that the user has expressed a preference for lightweight alternate content.

Examples

Basic usage

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

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

css
@media (prefers-reduced-data: no-preference) {
  @font-face {
    font-family: "Montserrat";
    font-style: normal;
    font-weight: normal;
    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",
    sans-serif;
}

Specifications

Specification
Media Queries Level 5
# prefers-reduced-data

Browser compatibility

See also

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