:stalled CSS pseudo-classThe :stalled CSS pseudo-class selector represents an element that is playable, such as <audio> or <video>, when playback is stalled. A resource is considered to be stalled if the user has requested playback of a specific position in the media resource, but it has failed to receive any data for some amount of time. This is different from :buffering in that the media element is unexpectedly not loading data when stalled (e.g., due to a network error) for around 3 seconds (the exact time is user agent dependent).
Note: Like with the :buffering pseudo-class, the element is still considered to be "playing" when it is "stalled". If :stalled matches an element, :playing will also match that element.
:stalled {
/* ... */
}:stalled {
outline: 5px solid red;
}
audio:stalled {
background-color: red;
}