Mobile Theme? – Need Help

I have a weird(?) problem with our website. I am using Firefox as my browser. When I look at the website (www.persimmonhollowvillalge.org) everything looks great. I can edit, update, etc. everything just fine.

Had a call this morning from one of my users who said our top banner was gone. I immediately check and everything looked great. Essentially told him he must have a browser problem as he was using the same browser as I was and it was working fine. On a lark, I looked at the website on another browser that i have (Chrome) and WOW! it looks just like he said that his did. Also noted at the bottom that it says something about a “Mobile Theme” switched to on. Anyone have any clue as to what is going on here? Why it works in one browser and not in another? How to get rid of this? Any help would be appreciated. Thanks.