Stopping a Banner from zooming an image

Hey Everyone,

So not sure how to explain this, but I have been designing a Hero banner for my homepage and made it 1400x500...yet when i put it up onto the website, it goes enlarged and not sure how or even if I can do anything about this. 

Found it does this also with the images, but this isnt as much of a concern and i can live with that. 

Any help is appreciated 🙏

Having the same issue.

https://www.portofinogin.com/