.yt-fixed-400{
  width: 400px;
  height: 230px;
  margin-left: auto;   /* allinea a destra nella colonna */
  overflow: hidden;
}

.yt-fixed-400 iframe{
  width: 400px !important;
  height: 230px !important;
  display: block;
  border: 0;
  max-width: none !important;
}