The simpler media website CMS
I have noticed that the Menu Manager extension is briefly displaying/flashing a vertical menu when refreshing or loading a new page. This behavior is observable here: https://www.loweprofile.com/gallery/ very obvious as it occurs at a slower rate. And here on a fresh install with zero code modifications: https://www.loweprofile.com/memorybook/
It seems to me that the 'vertical" menu used for mobile is briefly displaying. I am using the 'forked' iteration of zpBootstrap. This occurs on Chrome, Edge/PC or Safari/Mac OS.
Any help appreciated. Let me know if more info is neeeded.