Interesting, the problem is fixed on the main page, but not on the dedicated comments page https://teogaillard.itch.io/white-mirror/comments because you’ve limited the height of the black section, which is enough on the main page, while the comments page show comments at the top. But enough for now!
(maybe it would be nice to be able to select a different background on the dedicated comments page? feel free to drop a suggestion on the itch.io forum if you cannot find another solution)