.loader {
 border: 0 solid transparent;
 border-radius: 50%;
 width: 100px;
 height: 100px;
}

.loader::before,
.loader::after {
 content: '';
 border: 7px solid #ccc;
 border-radius: 50%;
 width: inherit;
 height: inherit;
 position: absolute;
 animation: loader 2s linear infinite;
 opacity: 0;
}

.loader::before {
 animation-delay: 1s;
}

@keyframes loader {
 0% {
  transform: scale(1);
  opacity: 0;
 }

 50% {
  opacity: 1;
 }

 100% {
  transform: scale(0);
  opacity: 0;
 }
}