Adjust number of columns for mobile on shop page

On my shop page, I would like to change the featured products at the top so they appear as 2 columns on mobile, to be the same as the categories that are underneath. What CSS code do I need to add to do this please?

And is there any way to get the featured products to appear below the categories, rather than above?

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