// Footer
window.addEvent("domready", fix_footer_at_bottom);
window.addEvent("resize", fix_footer_at_bottom);

function fix_footer_at_bottom() {
  var footer = $('footer');
  var footerBottom = footer.getCoordinates().bottom - (footer.marginFixedAt != null ? footer.marginFixedAt : 0);
  var windowHeight = window.getHeight();
  if (windowHeight - footerBottom > 20) {
    footer.style.marginTop = (windowHeight - footerBottom) + 'px';
    footer.marginFixedAt = (windowHeight - footerBottom);
  } else {
    footer.style.marginTop = '20px';
    footer.marginFixedAt = 20;
  }
}