function navOver(varItem) {
  el = document.getElementById(varItem);
  el.style.background = '#c0c0c0';
  el = document.getElementById(varItem + '_a');
  el.style.color = '#000';
}

function navOut(varItem) {
  el = document.getElementById(varItem);
  el.style.background = '#808080';
  el = document.getElementById(varItem + '_a');
  el.style.color = '#fff';
}

function navClick(varItem) {
  window.location = varItem + '.php';
}