.video-wrapper {
  position: relative;
  display: block;
  height: 0;
  padding: 0;
  overflow: hidden;
  padding-bottom: 56.25%;
  margin-bottom: 25px;
}
.video-wrapper > iframe {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}