document.getElementsByClassName = function(name) {
  var results = new Array();
  var elems = document.getElementsByTagName("*");
  for (var i=0; i<elems.length; i++) {
    if (elems[i].className.indexOf(name) != -1) {
      results[results.length] = elems[i];
    }
  }
  return results;
}

function roundCorners() {
  var elements = document.getElementsByClassName("rounded");
  for (var i=0; i<elements.length; i++) {
     insertCorners(elements[i]);
  }
}

function insertCorners(element) {
  var corners = new Array("northwest","northeast","southeast","southwest");
  for (var i=0; i<corners.length; i++) {
    var div = document.createElement("div");
    div.className = corners[i];
    element.appendChild(div);
  }
}

addLoadEvent(roundCorners);