In the plugin if you click newsletters>templates, and in the menu just under the subscribe field, “Settings” it brings up a field that says “Custom CSS.”
At the bottom of that field it says “CSS added to the main newsletter CSS.” I cannot figure out what this CSS actually does though. I don’t see any changes reflected in my template. I figure I’m just missing something or being exceptionally dense!
that custom css is added to the main newsletter code, can you please try to create a custom rule, add it there, save and then proceed to create a new newsletter (in which you’d expect to see that custom rule reflected)?