.wrap {
  position: relative;
  padding-bottom: 56.25%; /* proportion value to aspect ratio 16:9 (9 / 16 = 0.5625 or 56.25%) */
  padding-top: 30px;
  height: 0;
  overflow: hidden;
}
.wrap iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}