I edit markdown text in Emacs fullscreen. Naturally in fullscreen the text flows wider, from left edge of the display to the right, thereby necessitating more eye movements. I want to narrow down the entire text display to, say, 80 characters and position it in centre of the fullscreen Emacs. The emacs buffer should look as if there is unused empty space to the left and right of this centered narrow column of text that is being edited.
What is the simplest way to achieve this? (I could split into 3 buffers, but that's not simpler).