Landing Pages: Internal vs External Design Misalignment

I’ve had a landing page made for quite some time, used as an application to be a referral partner. I love it, but the mobile external view is different than how I’ve designed it. On the external view, the form is pushed all the way to the right side of the screen, making it both difficult to use and displeasing to the eye. However, in the internal system where I’ve designed it, I’ve tried to fix this by making sure the spacing and container padding are to my liking. It appears how I want internally, but externally it does not.
I also have a similar problem with a website webform pop-up.
Can this be fixed?