function menu_v1() {
  var getElm = document.getElementById("nav").getElementsByTagName("LI");
  var getCurrentElm = document.getElementById("current_top");
  for (var i=0; i<getElm.length; i++) {
    getElm[i].onmouseover=function() {
      this.className = "highlighted";
      getCurrentElm.id = "";
    }
    getElm[i].onmouseout=function() {
      this.className = "";
      getCurrentElm.id = "current_top";
    }
  }
}