Survey Form - Advice needed on how to make it responsive

The main issue is using constant absolute units for your elements.

I suggest you have a read over this survey form challenge walkthrough article explains this issue more in detail, plus tips and code samples.

Don’t rush, I suggest start something from zero.

Tip: start the layout first, don’t add any content(no text, no element, etc…). First make sure your layout is working.
Add each section of page a unique background color to see how do they located and sized in different screen sizes.

Keep going on great work, happy coding.