.c-stage-slide__iframe {
  height: calc(100vw / 16 * 9);
}
.c-intro__iframe {
  height: calc((100vw / 16 * 9) + 20px);
}
@media only screen and (min-width: 821px) {
  .c-stage-slide__iframe {
    height: calc((100vw - 83px) / 16 * 9);
  }
  .c-intro__iframe {
    height: calc(((100vw - 83px) / 16 * 9) + 42px);
  }
}
@media only screen and (min-width: 1026px) {
  .c-stage-slide__iframe {
    height: calc((100vw - 115px) / 16 * 9);
  }
  .c-intro__iframe {
    height: calc(((100vw - 115px) / 16 * 9) + 42px);
  }
}
@media only screen and (min-width: 1156px) {
  .c-stage-slide__iframe {
    height: 648px;
  }
  .c-intro__iframe {
    height: 690px;
  }
}