Wix Mobile and iPhone

I have built a beautiful desktop version of a website only to find that it looks like crap in mobile. I have the newest iPhone, my client has an 8plus and it looks horrible as well. My husband has a 5s, bless his heart, and it is perfect! Is there anyway to get a full screen while in mobile? This question has probably been asked before. There are large white borders on the mobile site when looking at it from a newer phone. This is for a travel business that relies highly on mobile. 80% of people booking travel do so from there mobile. Help me! If there is no help please let me know and off to WP I go.

Thank you

Sorry this may not be the right forum for this. Just looking for answers.