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.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
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: 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 |
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| Media Queries Level 5 # prefers-reduced-data |
Browser compatibility
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Legend
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- No support
- No support
- Experimental. Expect behavior to change in the future.
- See implementation notes.
- User must explicitly enable this feature.
See also
Save-DataHTTP header