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update

The update CSS media feature can be used to test how frequently (if at all) the output device is able to modify the appearance of content once rendered.

@media (update: < none | slow | fast >) {
  /* styles to apply if the update frequency of the output device is a match */
}

Syntax

The update feature is specified as a single keyword value chosen from the list below.

none: Once it has been rendered, the layout can no longer be updated. Example: documents printed on paper.
slow: The layout may change dynamically according to the usual rules of CSS, but the output device is not able to render or display changes quickly enough for them to be perceived as a smooth animation. Examples: e-book readers or severely underpowered devices.
fast: The layout may change dynamically according to the usual rules of CSS, and the output device is not unusually constrained in speed, so regularly-updating things like CSS Animations can be used. Example: computer screens.

Examples

HTML

<p>
  If this text animates for you, your browser supports `update` and you are
  using a fast-updating device.
</p>

CSS

@keyframes jiggle {
  from {
    transform: translateY(0);
  }

  to {
    transform: translateY(25px);
  }
}

@media (update: fast) {
  p {
    animation: 1s jiggle linear alternate infinite;
  }
}

Result

Specifications

Specification
Media Queries Level 4 # update

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`update-frequency`	113	113	102	No	No	No	113	113	102	No	No	No