Disable select all (ctrl+a)

Edit: I now see that you've applied it to the images within the .unselectable class. In Chrome these images are unselectable, so the issue appears to be browser-specific. To overcome this problem in whichever browser you're using you'll need to use JavaScript.

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It's all to do with the usage of your user-select:none. Currently, I can't see on your site where this has been applied, however applying it to the body tag does prevent Ctrl+A from selecting any content (in Chrome at least).

body {
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -o-user-select: none;
    user-select: none;
}

Try this

$(function(){   
    $(document).keydown(function(objEvent) {        
        if (objEvent.ctrlKey) {          
            if (objEvent.keyCode == 65) {                         

                return false;
            }            
        }        
    });
});