How to fix scroll issue in header

[CreatorTim]

Hey guys, when I open the header on mobile and start "scrolling," it scrolls all the way across the store.

How can I fix this? I want the header to be fixed in place and not scroll, without any bugs.

Here’s my store URL: https://1049xn-ya.myshopify.com/

I only need this for mobile

Thank you,
Tim