Apologies that I am not using the correct terminology as I have no clue what they are.

I would like to suggest having a toggle to make the "Unread" and the "Compose" buttons that are floating at the bottom of the screen to become static (?) at the top in the Header area, under or next to where it says "Inbox". I assume making these floating had something to do with the Categories that were implemented, but that was turned into a toggle. These floating buttons at the bottom of the screen hide emails and take up space especially on small devices.