var lastClass = 'none';
var lastId = 'none';
function hideRule(rulesClass) {
  var spaces = document.getElementsByClassName(rulesClass);
  for (var i = 0, length = spaces.length; i < length; i++) {
    Element.hide(spaces[i]);
  }
  if('none' != lastClass) {
    $(lastId).className = lastClass; 
  }
}
function showRule(ruleId, buttonId) {
  Element.show(ruleId, buttonId);
  lastId = buttonId;
  lastClass = $(buttonId).className;  
  $(buttonId).className = $(buttonId).className + ' active';
}