Hi there! That area of the closet with the hanging shirts is essentially a box constructed from plywood. You can see more details of that area on the first post on the closet:
https://www.findinglovely.com/master-closet-diy-part-i/

I came upon your post when I was looking for closet inspo. I’m planning on modeling my closet after seeing how beautiful yours turned out. I’ll have to make a few adjustments as my closet space is not as big, but I did want to please ask – in the third photo where most of your clothes are hanging, is that a platform or some type of bookcase from Ikea, or did your husband build that from hardware? Any help would be greatly appreciated. Thanks!

Hi Katherine, I feel like my clothes fit great, it’s the shoes that I could see being a problem with the Billy Bookcases. Mine are 6.5 or 7 and they are within and inch of the edge.