#loader {
  border: 12px solid #f3f3f3;
  border-radius: 50%;
  border-top: 12px solid #444444;
  width: 70px;
  height: 70px;
  animation: spin 1s linear infinite;
}

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

.center {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  margin: auto;
}