Keep cart icon from disappearing in bottom right corner?

Hello,

The website I will be launching is for a mental health foundation. It would be off-putting to have a shopping cart icon in the header. However, there is a shop on my site to purchase shirts to support the foundation. If you disable the shopping cart in the header, and someone adds something to their cart, the cart shows up in the bottom right corner. This is great. I'm happy with that functionality.

However, if someone goes to take a look in their cart and decides to go back into the site for any reason, the cart icon disappears from the bottom right corner. This effectively means that unless they add another item to their cart, that icon never comes back and there is no way for them to get back to the cart to finish their purchase. I'm looking for some code to force that cart icon to stay in place as long as something is in the cart. Any help is greatly appreciated.

https://beige-lobster-adm6.squarespace.com/

Password: square207

Can you share link to a product? We can add it to cart to check cart icon.