.c-stage-slide__iframe {
  height: calc(100vw / 16 * 9);
}
@media only screen and (min-width: 821px) {
  .c-stage-slide__iframe {
    height: calc((100vw - 83px) / 16 * 9);
  }
}
@media only screen and (min-width: 1026px) {
  .c-stage-slide__iframe {
    height: calc((100vw - 115px) / 16 * 9);
  }
}
@media only screen and (min-width: 1156px) {
  .c-stage-slide__iframe {
    height: 648px;
  }
}