.article.widget-default-embed iframe {
  width: 100%;
}

/* Grade A */
/* Grade B */
/* Grade C */
@media (max-width: 767px) {
  .article.widget-default-embed {
    width: 100%;
  }
}
/* Grade D */
@media (max-width: 575px) {
  .article.widget-default-embed {
    width: 100%;
  }
}