body, html {
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
}
  
.loader {
  display: flex;
  justify-content: center;
  align-items: center;
  
  border: 6px solid #f3f3f3;
  border-radius: 50%;
  border-top: 6px solid #3F51B5;
  width: 40px;
  height: 40px;
  -webkit-animation: spin 1s linear infinite; /* Safari */
  animation: spin 1s linear infinite;
}

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

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