After creating a scroll menu, the Content widens the screen issue.

[CupiShupi]

Hello. I added a horizontally scrollable image menu to my HTML site with CSS. I created it using ul and li elements. The site is perfect with no issues. However, after implementing it, I'm receiving a Mobile Usability - Content wider than screen warning in the Search Console. What could be the reason for this? Additionally, there is a possibility that it could be Google-related.