var css_string = '' + 
            '#vakata-dragged ins { display:block; text-decoration:none; width:16px; height:16px; margin:0 0 0 0; padding:0; position:absolute; top:4px; left:4px; ' + 
            ' -moz-border-radius:4px; border-radius:4px; -webkit-border-radius:4px; ' +
            '} ' + 
            '#vakata-dragged .jstree-ok { background:green; } ' +