@keyframes spinner {
  to {transform: rotate(360deg);}
}
 
.spinner:before {
  content: '';
  box-sizing: border-box;
  position: relative;
  display: inline-block;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 2px solid #ccc;
  border-top-color: #000;
  animation: spinner .7s linear infinite;
}