javascript making a jquery countdown work with UTC times

I am using this jquery countdown:

http://ift.tt/1AVC432

I initialize it like this:

        <div id="clock"></div>
        <script type="text/javascript">
            $('#clock').countdown('2015/03/27 00:00:00')
              .on('update.countdown', function(event) {
                var format = '%H:%M:%S';
                if(event.offset.days > 0) {
                  format = '%-D day%!d ' + format;
                }
                $(this).html(event.strftime(format));
               })
             .on('finish.countdown', function(event) {
               $(this).html('FINISHED!');
             });
        </script>

The target time I use is in UTC but it will only work if people enter the site in UTC. I need to make it work in all the timezones, I mean, wherever the user is from it always has to see the same time left...

How can this be done?