function overMain(element) {
  var el     = document.getElementById(element);
  var el_sub = document.getElementById(element+"_sub");
  el.className = "active";
  if (el_sub) {
    el_sub.style.display = "block";
  }
}

function outMain(element) {
  var el = document.getElementById(element);
  var el_sub = document.getElementById(element+"_sub");
  el.className = "";
  if (el_sub) {
    el_sub.style.display = "none";
  }
}