Additional CSS for Twenty Seventeen – different header image on hompage

I would like to show a different header image on all of the posts and pages of my Twenty Seventeen site than on the home page. Mostly because the header image looks great on the home page, but on other pages the header is narrow and cuts off the top and bottom of my header image, and I would like to display an more appropriate image.

I was able to find this custom CSS to remove the header from everywhere but home:

body:not(.home) 
  .wp-custom-header img { 
	display: none; 
}

but I’m not sure how to show a different image on all pages besides Home. I tried this:

body:not(.home) 
  .wp-custom-header img { 
	background-image: url("images/short-header.jpg"); 
}

but it didn’t work, i get just a portion of the main header image. Also I’m not sure exactly how much of the web address I need to put in the url section, does it start from the https:// or from a subfolder (such as wp-content/uploads) of my WordPress site?

I am relatively new to css and am currently learning how to implement child themes, but I was hoping I could do this in the Additional CSS section for now to get the website operational.

Thanks!

The page I need help with: [log in to see the link]