I'd like to have emacs not to have a background color when I open a frame in the terminal. I'm using a terminal with a translucent background, and characters with a background color are not "see-through". TERM is set to "xterm-256color".

How do I get emacs to use the default background color (no color at all), when the frame is not graphical?

Edit: I've got it, sort of:

(add-to-list 'custom-theme-load-path "~/.emacs.d/themes")
(load-theme 'my-awesome-theme t)

(defun on-frame-open (frame)
  (if (not (display-graphic-p frame))
    (set-face-background 'default "unspecified-bg" frame)))
(on-frame-open (selected-frame))
(add-hook 'after-make-frame-functions 'on-frame-open)

I put the above code in my init file, but only suppresses the background when opening an emacsclient in a terminal, and not emacs itself (i.e. only when invoked with emacsclient -t and not when invoked with emacs). Adding an extra (unless window-system (set-face-background 'default "unspecified-bg" (selected-frame))) doesn't work and only confuses graphical frames.

Any ideas on why this might happen?