possible to make one buffer transparent/dim?

Question

I usually use emacs in a two column view, with two buffers side by side vertically. I'd like to make the buffer that I'm not focused on dim/transparent or something - some way to more easily differentiate it from the one that currently has focus.

I found this snippet that I can use to make all of emacs transparent when it loses focus:

(set-frame-parameter (selected-frame) 'alpha '(100 80))
(add-to-list 'default-frame-alist '(alpha 100 80))

But I want to make just one buffer transparent/dim when it loses focus. Is there a way to do this?

Answer 1

I do not use transparent feature but gold-ratio can do some things like focus in window.