#plan{
  width:750px;
}

.row{
  margin-bottom: 10px; 
}


.seat6{
  margin-left: 40px;
}
.seat20{
  margin-left: 40px; 
}

#A .seat6, #B .seat6, #C .seat6, #D .seat6{
  margin-left: 360px; 
}

#O .seat6, #P .seat6{
  margin-left: 240px; 
}