:fullscreen
Targets an element while it is being displayed in the browser's full-screen mode (e.g., when a video or a photo is expanded to fill the whole monitor).
Quick example
video:fullscreen {
/* Keeps the background black during full-screen video playback */
background-color: black;
border: none;
}:fullscreen Browser Support
Limited availability94% global usage
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Not ready for production without a fallback.
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