Menu Nav on Mobile Taking Up Whole Page

This is my first website and I am still learning.

My small shop website nav menu is taking up the whole page on mobile. I want the viewers to be able to see at least 20-30% of the page they are on while they are navigating through menu.

This is my website menu on mobile currently –

I want the menu on mobile view to look like this –

The page I need help with: [log in to see the link]