Optimising image block height vs. width

Site URL: https://www.goodcopybadart.com/exec-sum

It seems that when putting multiple image blocks in a row Squarespace (at least the Avenir template) optimises them to be similar in width. How can I reverse this so that the images would be similar in height, not in width? 

The images in my case are originally taken from a comic book with 9 panels (3 rows of 3 pictures), but when I upload them one by one using image blocks the structure breaks because of how they are forced to be similar in width instead of height.

Hopefully someone has the right answer, Googling for it didn't work for me :)

Add to Page Settings > Advanced > Header

<style>
  @media screen and (min-width:768px) {
  .sqs-block-image img {
    display: block;
    width: auto !important;
    height: 100% !important;
    top: 0 !important;
}
  .sqs-block-image .image-block-outer-wrapper:not(.image-block-v2) .image-block-wrapper {
    padding-bottom: 120% !important;
}
  }
</style>