Discrepancies with screensizes

Hey! I really need help with a project. It’s almost done, but the client and I are seeing some discrepancies between screen sizes. For example, I see the webpage correctly on my 15" MacBook Pro whereas he sees it a bit messed up. Same thing happens with mobile phones.

I don’t really know what to do, since it’s like being blindfolded in a storage. Any help is more than appreciated :S

Thank you


Here is my site Read-Only: https://preview.webflow.com/preview/gamesprout?utm_medium=preview_link&utm_source=designer&utm_content=gamesprout&preview=8198a579b4812062ff0ce3c23de9ab5b&mode=preview
(how to share your site Read-Only link)