Judging by the website links you previously sent me in the email, I believe you have figured out how to use the theme. Anyway, I hope you are finding the User Guide useful. And don’t hesitate to let me know if you need anything else.
Please correct me if I am wrong, but during our communication we have established that the issue you are having is not on the side of the theme, as the theme demo does not have this issue in Firefox. Which, in turn, looks like an indication of the issue being on the side of the environment you are running the theme in. Maybe it’s caching, maybe it’s the server configuration, etc. At that point I believe it was evident that it makes sense to hire a freelance WordPress expert to sort that out. I apologize if I haven’t communicated this clearly enough.