.responsiveContent {
  position: relative;
  height: 0;
  overflow: hidden;
  padding-bottom: 56.2%;
  margin-bottom: 20px;
}
.responsiveContent iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;  
  border: 2px solid #00f;
}