@supports object fit

style.scss

// This trick will make your image 30px wide and
// will automatically adjust the height of the
// image based on its aspect ratio. However, if
// the browser supports `object-fit`, the image
// will be made 30px by 30px and will size the
// image based on its aspect ratio
// (like background-size: cover)

img {
  width: 30px;
  height: auto;
}

@supports (object-fit: cover) {
  img {
    height: 30px;
    object-fit: cover;
  }
}