I am already using email forms and I've integrated MailChimp. However, email forms only allows for putting a form on a page. I want to have a subscriber pop-up. MailChimp has functionality for this but you then need to add a script into the header.php.
So, I was able to add the code into my functions.php of my child theme and it worked nicely. However, when I tried to edit a page in Cornerstone, it gave an error message and went into skeleton mode.
Once I removed the code in functions.php, Cornerstone worked again.
Can you please advise how I should fix this issue?