Change header image to resize correctly

My site:

So I’ve been trying many different codes to get some of my page to show. I’d love to have my page show the header image the same way it does with my mobile page.

What it looks like:

What I want it to look like:

The way the mobile page displays the image is perfect. I want the main website to display the image in the same way But everything else to display normally.

Hello there,

Does it happen on a specific screen resolution? To know your current screen resolution, visit this site.