div#left_side_bar {
  float:left;
  width:39%;
  margin-left:-38.9%;
  padding: 0;
}
div#right_side_bar {
  float:right;
  width:15.4%; /* If the side column is the same width as the centre column then this percentage is 100% */
  margin-right:-15.3%; /* This is less than the width because this div must have some real existence in its parent div */
}
div#footer { 
  clear:both;
  border-top: none;
  background-color:#fff;
 }