I like the little day bed and the window and beat board walls. day bed on plywood base with built in table. we would put the long edge further back for under the bed storage space. I also would want to paint it like white or something.
DIY "Floating Bookshelf" Add two tiny nails just under the brackets. Open the bottom book, and used the nail to hold the cover closed. This hides the bracket completely, making the bookshelf invisible.