window.addEvent('domready',function() {

   // Basculement des pages
   if($('page2')){
      $('page_1_selector').addEvent('click', function(event){
          togglePage1(this.getProperty('color'));
          return false;
      });
      $('page_2_selector').addEvent('click', function(event){
          togglePage2(this.getProperty('color'));
          return false;
      });
   }
});

function togglePage1(color){
    $('page2').setStyle('display', 'none');
    $('page1').setStyle('display', 'block');
    $('page_1_selector').addClass('selected');
    $('page_2_selector').removeClass('selected');
    $$('#content .left_bloc').setStyle('background-color', color);
}

function togglePage2(color){
    $('page1').setStyle('display', 'none');
    $('page2').setStyle('display', 'block');
    $('page_2_selector').addClass('selected');
    $('page_1_selector').removeClass('selected');
    $$('#content .left_bloc').setStyle('background-color', color);
}