Code for bannersize

Site URL: https://www.bestsupplyatl.com/

I created this page on my mac, so whenever I open this page on mac, the banners looks perfectly fine.

But, whenever I open it on windows with wide screen, regular screen, and even on the phone, the pictures are just cutting off. 

Any recommendations for this issue?

Also, the pictures you see on banner spot, are not on banner page.  I deleted the banner image, and uploaded the pictures on my intro, so I can make slideshows on

banner spot. 

Thank you.