Customising .init.el for root user

[Johnny]

Hi,

Starting emacs as my normal user running a root terminal (via su), I want
emacs to start with some specific parameters that does not apply when
running as the normal user. Specifically, I want the color to be
distinct so that it is obvious which emacs is the root session. 

I understand that by default the users init file is used [1]. This
never worked well for me, defaulting into basic settings, but after
looking into it and replacing any "~" references with full paths, it
works as intended.
However, this gives /all/ the defaults in the user init file, such as
the color-theme used. I already use the same init file for multiple
(well, two anyhow) computers and use a check which machine I am on for
some dedicated settings, e.g.
,----
| (when (string= (system-name) "the other machine")
|       ..run some customisations...
|       )
`----
Is there any similar way to check whether the session was started with
root privileges to set customisations? E.g. 
,---- 
| (when (session-started-as-root)
|         (load-theme 'wheatgrass)
|         )
`----
with a 'session-started-as-root' function? Better methods??

I found one way is to default to a root init file by defining an alias
in the root .bashrc as
,----
| alias emacs="emacs -u root"
`----
however it would be nice to have only one init file to keep track of as
many tweaks are nice to have in all sessions.

Any ideas / good practices?

All the best 

Johnny


Footnotes: 
[1]  (info "(emacs)Find Init")

-- 
Johnny