document.observe('dom:loaded', search_box_observer);
function search_box_observer() {
  // Clear the 'Search' text from the search form on focus
  $('search_form_input').observe('focus', function() {
    if ($('search_form_input').getValue() == 'Search') {
      $('search_form_input').addClassName('active');
      $('search_form_input').value = '';
    }
  });
  
  $('search_form_input').observe('blur', function() {
    if ($('search_form_input').getValue() == '') {
      $('search_form_input').removeClassName('active');
      $('search_form_input').value = 'Search';
    }
  });
}