.iframe-container {
  overflow: hidden;
  // Calculated from the aspect ration of the content (in case of 16:9 it is 9/16= 0.5625)
  padding-top: 56.25%;
  position: relative;
}
 
.iframe-container iframe {
   border: 0;
   height: 100%;
   left: 0;
   position: absolute;
   top: 0;
   width: 100%;
}

.display-1 {
  font-size: 6rem;
  font-weight: 300;
  line-height: 1.2;
}

.center-block {
  width: 50%;
  padding: 5px;
  background: #ffffff;
}