How to Make Contact Form Responsive

I had a look, I’m not expert but this article might help point you in the right direction
Seems to be something in the contact form 7 that needs adjusting. CSS perhaps?

https://www.zeeronsolutions.com/how-to-make-contact-form-7-plugin-fields-responsive-full-width/

I’m having enough trouble with my own contact form so I don’t have time to look into it further for you sorry. Someone else with more knowledge may be able to help.