Switching between desktop and mobile images within a gallery

I have two sets of images, one for desktop and one for mobile, each within the same gallery.  The desktop version has a more elaborate layout that will not read in mobile so I want to use css to show/hide depending on the screen size.   I'm using the code below and it's working perfectly except for one issue.  On the desktop version after the last image instead of returning to the beginning you see a black black screen.  The mobile images are hidden but the navigation is still loading the blank pages.  How do I point the link back to the first image?

/* Mobile*/
    @media only screen and (max-width: 800px) {
     #collection-############################### .slide:nth-child(-n + 22) {
      display:none;
     }
      }
 
  /*Desktop */
    @media only screen and (min-width: 800px) {
    #collection-############################### .slide:nth-child(n + 23) {
      display:none;
    }
   }

If you used max-width:800px for mobile, then desktop min-width:799px

also, can you share link to gallery on your site? difficult to help without checking url 

Hi @tuanphan.  I switched the desktop to 799px but it didn't help the problem.  The site is still private so I'll direct message with a link.