.embed-responsive {
  display: block;
  overflow: hidden;
  padding: 0;
  position: relative;
  width: 100%;

  &::before {
    content: '';
    display: block;
  }

  embed,
  iframe,
  object,
  video,
  .embed-responsive-item {
    border: 0;
    height: 100%;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    width: 100%;
  }
}

.embed-responsive-1by1 {
  &::before {
    padding-top: percentage(1 / 1);
  }
}

.embed-responsive-4by3 {
  &::before {
    padding-top: percentage(3 / 4);
  }
}

.embed-responsive-16by9 {
  &::before {
    padding-top: percentage(9 / 16);
  }
}

.embed-responsive-21by9 {
  &::before {
    padding-top: percentage(9 / 21);
  }
}