Well, after some tweaking, I have been able to use the Mailchimp original code but keeping some style that goes with the theme.
It is almost less “user-friendly” than what you’ve developed but at least, it works for me.
I discovered Pluton a few time ago, and I’m really happy with it and overall with the support you’ve provided.
(Whereas I’m just a “Free version” user)
Thanks a lot again.
I will spread the word… for sure!