var stripe = function() {
  var tables = document.getElementById('content').getElementsByTagName("table");
  if (!tables[0]) { return; }
  var table = tables[0];
  var trs = table.getElementsByTagName("tr");
  var even = false;
  for (var j = 0; j < trs.length; j++) {
    if (even) {
      trs[j].className += " alt";
    }
    even = !even;
  }
}
window.onload = stripe;