.centered {  
  position:fixed;
  z-index: 100;  
  top:50%;  
  left:50%; 
  margin:-100px 0 0 -100px;  
}

.centeredDiv {  
  position:fixed;
  z-index: 100;  
  top:10%;  
  left:25%; 
  margin:-100px 0 0 -100px;  
}