/* The .container and .responsive-iframe code below is from
   https://www.w3schools.com/howto/howto_css_responsive_iframes.asp */

   .container16x9 {
    position: relative;
    overflow: hidden;
    width: 100%;
    padding-top: 56.25%; /* 16:9 Aspect Ratio (divide 9 by 16 = 0.5625) */
    margin-bottom: 1.15rem;
  }
  
  .responsive-iframe {
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    width: 100%;
    height: 100%;
  }