.center-content {
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
}

iframe {
    overflow: hidden;
    width: 100%;
    height: 100vh;
}

#block21 {
    align-items: center;
}

#block21 .has-medium-font-size {
    align-items: center;
    line-height: 1;
}