Responsive Base Apparel Site

I had two issues :

• The first was that the page works properly for sizes up to 1440px. After that, the image is too small to properly cover its portion of the container. Is there a way to fix this?
• The second issue I encounter was with form validation. I tried looking online at examples but struggled to find a good example. What are some things you would typically implement to validate a form in JS.

Any help would be greatly appreciated. Thank you in advance!