I’m not exactly sure which content your losing, but one thing to point out is that you’ve set your body element (“Body 3”) to overflow: scroll on your tablet and mobile breakpoints which is causing some weird behavior:
I’d recommend removing that from the Tablet, Mobile Landscape, and Mobile Portrait breakpoints to see if that doesn’t fix the issue you’re seeing. Normally it’s best to keep the Body overflow style at the default—especially if your just starting out—but if you’re using it for something specific let me know so I could recommend an alternative.
If that doesn’t happen to fix the issue your noticing then feel free to reach out with a bit more information and I’d be happy to take another peek