addLoadEvent(zebraTable);

function zebraTable() {
	if (!document.getElementsByTagName) return;
	var row = document.getElementById('zebra').getElementsByTagName('tr');
	for (var i=1;i<row.length;i+=2) {
		row[i].className = 'alt';
	}
}

function addLoadEvent(func) {
  var oldonload = window.onload;
	if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}