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

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 */


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


Once it has been rendered, the layout can no longer be updated. Example: documents printed on paper.


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.


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.



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


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

  to {
    transform: translateY(25px);

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



Media Queries Level 4
# update

Browser compatibility

BCD tables only load in the browser

See also