function changeStyle(obj){
    
 if (document.getElementById("op_" + obj).className == "active")
 {
  document.getElementById("op_" + obj).className = "";
  document.getElementById("part_" + obj).className = "yincang";
  return;
 }


 for(x = 1; x <= 27 ; x++){
  document.getElementById("op_" + x).className = "";
 }  
 document.getElementById("op_" + obj).className = "active";

 
 for(x = 1; x <= 27 ; x++){
  document.getElementById("part_" + x).className = "yincang";
 }  
 document.getElementById("part_" + obj).className = "popup";

}