@media screen and (max-width: 840px){
    #block01 {
    order:2;
  }
  #block02 {
    order:1;
  }
  #block03 {
    order:2;
  }
 #block04 {
    order:1;
  }
  #block05 {
    order:2;
  }
  #block06 {
    order:1;
  }