.loader {
  border: 6px solid #f3f3f3;
  border-radius: 50%;
  border-top: 6px solid #3498db;
  width: 40px;
  height: 40px;
  
  -webkit-animation: spin 0.8s linear infinite; /* Safari */
  animation: spin 0.8s linear infinite;
  
  position:absolute;
 	left:50%;
 	top:50%;
 	margin-left:-26px;	/*size is 52x52px with boarders*/
 	margin-top:-26px;
  z-index: 500;
  visibility: hidden;
}

/* Safari */
@-webkit-keyframes spin {
  0% { -webkit-transform: rotate(0deg); }
  100% { -webkit-transform: rotate(360deg); }
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}