Zoho Campaigns Forms not Responsive on Website

Zoho Campaigns Forms not Responsive on Website

I have a mobile responsive Zoho Sites website and when I add a Zoho Campaigns form, it is not responsive. I have used the website code and ensured that the 'responsive' checkbox is selected. But, the form is not responsive to mobile. I have attached a screenshot from my mobile.

The first form is using a Newsletter element from Zoho Sites, which works well. But with double opt-in I cannot see conversion rates. So I want to change to Zoho Campaigns so that I can see all the data. I have tried to match my font and style as closely as possible with the limitations in Zoho Campaigns, and I am pretty happy with the result; except that it is not responsive - this is as non-negotiable. 

The second screenshot is how it looks on the web. I like how it looks there. It is just the mobile view that I need help with. 

Can you please help?