Sign-up CTA in header of Casper theme using code injection

Hey everyone,

I’m looking to modify the Casper theme header into a hero section with a CTA, but I want to do it using code injection only.

I would especially like to have a sign-up form in the middle of the header image, just like on the Edition theme, to harvest free sign-ups easier and quicker.

Does anyone know how to do that?

And, if you have more ideas for modifying the header section into a hero section using only code injection, I would really appreciate it.

Thanks in advance.