How To Make Embedded Videos From Media Manager Responsive in Drupal 9

To make embedded video responsive you should do these steps:

1. Install module Asset Injector
2. Create new CSS Injector with code below, and save.
3. Clear cache

.field--name-field-media-oembed-video {
  position: relative;
  overflow: hidden;
  width: 100%;
  padding-top: 56.25%;
}
.media-oembed-content {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  border: 0;
  width: 100%;
  height: 100%;
}

That`s it. Enjoy!