These are jpeg images that are being resized by the theme and are losing their resolution ratio. They should maintain their 16X9 resolution ratio. Screen size is irrelevant. As you can see by the screenshots linked in my previous post, the images look the same on both desktop browsers and mobile browsers alike. When the theme’s styling resizes the jpeg featured images for the blog archive pages, it should retain their resolution ratio of 16X9.
What changes to the CSS in this theme need to be made so those graphics maintain their 16X9 ratio when being resized?