function headerOverEffect(object) {
  if (object.className == 'navTableNormal' ) object.className = 'navTableOver';
}

function headerOutEffect(object) {
  if (object.className == 'navTableOver') object.className = 'navTableNormal';
}

var x = 0;
var step = 2;
var tid;

function moveBackground() {
	x += step;
	document.body.style.backgroundPosition = x+'px 70px';
}