function removeClass(el, className) {
  if (!(el && el.className)) return;
  var classes = el.className.split(" ");
  var newClasses = new Array;
  for (i = 0; i < classes.length; ++i)
    if (classes[i] != className) newClasses[newClasses.length] = classes[i];
  el.className = newClasses.join(" ");
}

function addClass(el, className) {
  el.className += " " + className;
}