document.observe("dom:loaded", function() {
  $('alaska-header').observe('click', function(event) {
  		filter('alaska');
  });
  $('canada-header').observe('click', function(event) {
  		filter('canada');
  });
  filter('alaska');
});

function filter(type) {
	$('alaska-header').removeClassName('selected');
	$('canada-header').removeClassName('selected');
	$(type + '-header').addClassName('selected');
	$('alaska-intro').hide();
	$('alaska-cruiselines').hide();
	$('canada-intro').hide();
	$('canada-cruiselines').hide();
	$(type + '-intro').show();
	$(type + '-cruiselines').show();
}