.youtube-video-container {
  position: relative;
  width: 50%;            /* half screen width */
  margin: 50px auto;      /* center + top/bottom spacing */
  overflow: hidden;
}

@media screen and (max-width: 750px) {
  .youtube-video-container {
    position: relative;
    width: 90%;            /* half screen width */
    margin: 20px auto;      /* center + top/bottom spacing */
    overflow: hidden;
  }
}


.youtube-video-container::after {
  content: "";
  display: block;
  padding-top: 56.25%;    /* 16:9 aspect ratio */
}

.youtube-video-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;            /* fill container */
  height: 100%;           /* maintain ratio */
  border: 0;
}