var liListElement;

function init_menu(){

 if (!document.getElementById) return;

  var menu = document.getElementById("mainMenu");
  liListElement = menu.childNodes;

  for (var i = 0; i < liListElement.length; i++) {
    var node = liListElement[i];
      node.onmouseover = function (){
      menu_hover_change(this);
    }
  }
}

function menu_hover_change(el){
  
  for (var i = 0; i < liListElement.length; i++) {
    var node = liListElement[i];
    if(node.tagName=="LI"){
      
      var children = node.getElementsByTagName('a');
      children[0].className="main";
  
      var children = node.getElementsByTagName('ul');
      if(children.length>0){
        children[0].className="";
      }
    }
  }
  
  var children = el.getElementsByTagName('ul');
  if(children[0]){
    children[0].className="hover";
  }
  
  var children = el.getElementsByTagName('a');
  children[0].className="main hover";
 
}