var duration = 500;  /* 1000 millisecond fade = 1 sec */
var steps = 50;       /* number of opacity intervals   */


function fadeIn(eid){
  for (i = 0; i <= 1; i += (1 / steps)) {
    setTimeout(setOpacity, i*duration, i, eid);
  }
}

function fadeOut(eid) {
  for (i = 0; i <= 1; i += (1 / steps)) {
    x = 1 - i;
    setTimeout(setOpacity, i*duration, x, eid);
  }
}


function setOpacity(level, eid) {
  var element = document.getElementById(eid);
  element.style.opacity = level;
  element.style.MozOpacity = level;
  element.style.KhtmlOpacity = level;
  element.style.filter = "alpha(opacity=" + (level * 100) + ");";
}