_video.scss

// Responsive Video using CSS only
.video {
  height: 0;
  overflow: hidden;
  padding-top: 35px;
  padding-bottom: 56.25%; // 56.25% = 16x9
  position: relative;

  &--full {
    padding-bottom: 75%; // 75% = 4x3
  }

  iframe {
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
  }
}