WebVTT: The Web Video Text Tracks Format

Spec The ::cue pseudo-element (with no argument) matches any list of WebVTT Node Objects constructed for the matched element, with the exception that the properties corresponding to the background shorthand must be applied to the WebVTT cue background box rather than the list of WebVTT Node Objects.

MDN The ::cue CSS pseudo-element matches WebVTT cues within a selected element. This can be used to style captions and other cues in media with VTT tracks.

video {
  width: 100%;
}

video::cue {
  font-size: 1rem;
  color: yellow;
}

::cue(u) {
  color: red;
}

<video controls src="https://developer.mozilla.org/shared-assets/videos/friday.mp4">
  <track
    default
    kind="captions"
    srclang="en"
    src="https://developer.mozilla.org/shared-assets/misc/friday.vtt" />
  Sorry, your browser doesn't support embedded videos.
</video>

::cue

::cue(selector)

Specification ↗ MDN reference ↗

Spec The ::cue-region pseudo-element (with no argument) matches any list of WebVTT region objects constructed for the matched element.

::cue-region

::cue-region(selector)

Specification ↗