I am a Vim user and i recently decided to try
Emacs Spacemacs, i have a problem setting up custom highlighting, i set some lines like the following in my .spacemacs (i guess it's the same problem in your .emacs):
(set-face-background 'font-lock-comment-face nil)
The idea is to always disable the background highlighting of "commented areas" but it has a problem, it works fine when starting Emacs but changing the theme resets it (the new theme overwrites it).
There is the same problem in Vim which is easily fixed by loading the custom colors after a theme has been loaded :
autocmd ColorScheme * call LoadMyCustomHighlighting()
How do you translate that in elisp?
Note: I found what seems to be a similar question here but it don't understand it (elisp noob), i would want some actual working code with a basic explanation.