function rgb (a, b, c) {
  function toHex (d) {
    var d = d.toString(16);
    if(d.length == 1)
      d = '0' + d;
    return d;
  }
  return '#' + toHex(a) + toHex(b) + toHex(c);
};

function changeBgColor (className) {
  var bg = YAHOO.util.Dom.getStyle(document.body, 'backgroundColor');
  try { bg = eval(bg); } catch (e) {};

  if(bg.toLowerCase() == '#ffffff'){
    var ele = YAHOO.util.Dom.getElementsByClassName(className);
    for(var i=0;i < ele.length;i++){
      YAHOO.util.Event.on(ele[i], 'mouseover', function () { this.style.backgroundColor = '#ffffbb' });
      YAHOO.util.Event.on(ele[i], 'mouseout',  function () { this.style.backgroundColor  = bg });
    }
  }
}