Please share your store password.
So that I will check and let you know the exact solution here.
Hey there @rhinosled,
You need to move the following description div element (With class rte product-single__description) element outside of parent div (With class grid product-single)
You can find the element in Product-template.liquid (In Sections folder) file. You can use CTRL + F to search the element using it's class "product-single__description"
I hope that makes sense.