That most recent screenshot of yours, Blossom, would be intolerable for me, due to the extreme waste of screen real estate -- huge empty margins on all 4 sides. That is one of the worst flaws of Kindle software to me (and iBooks, too): the inability to reduce margins on all 4 sides to a minimum.
To each their own, of course. You seem happy with the margins just as they are in your Kindle software. Good for you.