Maintain aspect ratio of square images in responsive design

Ever since the change to fluid engine, I'm having trouble with square shaped images. I think it has to do with flexbox but I'm not sure how to fix it... I have images, such as the one on the Homepage and the four on the About page, that I want to appear as square, even when the size of the screen changes. Instead, the aspect ratio of the image changes with the responsiveness.

I know I can create sections using the classic builder to achieve this, but does anyone have a workaround for fluid engine?

Thank you in advance!

site: https://sistersnacking.squarespace.com/

pw: 20reformette23

Typically you need to set the image to FIT rather than FILL and adjust the block alignment. FIT means that the image doesn't crop so should maintain it's aspect ratio.

Thank you, that worked! I just had to change the code I was using to give the images a border.