function changeClass(id, c) {
    getElement(id).className = c;
}

function getElement(psID) { 
   if (document.all) { 
      return document.all[psID]; 
   } else if (document.getElementById) { 
      return document.getElementById(psID); 
   } else { 
      for (iLayer = 1; iLayer < document.layers.length; iLayer++) { 
         if (document.layers[iLayer].id == psID) 
            return document.layers[iLayer]; 
      }       
   } 
   return Null; 
}