function ch_search2() {
  if (document.getElementById('search_field').value == 'Поиск') {
    document.getElementById('search_field').value = '';    
    //document.getElementById('search_field').style.color = '#000000';    
  }
}

function drop_search2() {
  if (document.getElementById('search_field').value == '') {
    //document.getElementById('search_field').style.color = '#666666';
    document.getElementById('search_field').value = 'Поиск';      
  }
}