.loader {
  border: 10px inset tomato;
  padding: 12px;
  transform: rotate(45deg);
  animation: loader1 1s ease-in-out infinite;
}
@keyframes loader1 {
  0% {
    opacity: 0;
  }
  50% {
    opacity: 1;
    transform: scale(1.5);
  }
  100% {
    opacity: 0;
  }
}