@Billiam: That sounded like it was supposed to work, but alas, it didn't. But thank you for trying!
@Cimento: Sorry, that was poorly worded. I only meant that, when editing the theme of the page, I had set the screenshot dropdown to hidden, to no longer display the screenshot sidebar. Instead, I pasted the raw url of the images into the games description.
I have found a workaround at this page: It simply uses 1000px wide images instead of 1080px, so that the margin doesn't matter!
https://colorfiction.itch.io/blue