Jquery Lazy Loading after image load, css is not applied

I would suggest doing it this way :

    $('img.lazy').Lazy({

        scrollDirection: 'vertical',                
        visibleOnly: false,               
        afterLoad: function(element) {                   
            element.css('border', 'thick solid chartreuse');                  

        }
    });

By using border you won't be missing any parameters! :) Also less code to do the same thing is always better.

I prepared a demo with a large file and a loading animation so you could actually notice the lazy loading before the image loads and the border takes effect.

JSFiddle demo

Border-style CSS attribute is required. Default value is none, so border is not displayed.

$('img.lazy').Lazy({
    scrollDirection: 'vertical',                
    visibleOnly: false,               
    afterLoad: function(element) {                   
        element.css('border-width', 'thick');
        element.css('border-color', 'chartreuse');
        // add border-style and border becomes visible                    
        element.css('border-style', 'solid');
    }
});

Live demo