Apply Fancybox to image links and galleries and exclude mobile devices.
var pixelRatio = window.devicePixelRatio || 1;
// applies Fancybox only if device screen is wider than 768px
if(window.innerWidth/pixelRatio > 768 ) {
jQuery("a[href$='.jpg'],a[href$='.jpeg'],a[href$='.png'],a[href$='.gif']").attr('rel', 'gallery').fancybox({
});
}
Install Fancybox then add this Javascript before the closing <body>
tag to apply Fancybox to image links and gallery links. Adjust the screen width to your needs (set here for 768px and less).