sass mixin - aspect-ratio()

// aspect-ratio()
//
// Use on a container that you want to maintain a specific aspect ratio when scaling
//
// $width - in pixels
// $height - in pixels

@mixin aspect-ratio($width, $height) {
  position: relative;

  &:before {
    display: block;
    content: '';
    width: 100%;
    padding-top: ($height / $width) * 100%;
  }
}