function previous_offer(element) {
  hide_highlighted_offers();
  if ($(element).previous()) {
    $(element).previous().addClassName('active');
  } else {
    $$('.highlighted-offer').last().addClassName('active');
  }
  slide();
}

function next_offer(element) {
  hide_highlighted_offers();
  var next = $(element).next('div')
  if (next != undefined) {
    next.addClassName('active');
  } else {
    $$('.highlighted-offer').first().addClassName('active');
  }
  slide();
}

function hide_highlighted_offers() {
  $$('.highlighted-offer').each(function(element) {
    element.removeClassName('active')
  });
}

function slide() {
  Effect.ScrollTo('second-column');
}