.hello-world {
  margin: 200px 0;
  font-size: 70px;
  text-align: center;
}

.hello-world__i {
  display: inline-block;
  -webkit-animation: rotate 4000ms infinite linear;
          animation: rotate 4000ms infinite linear;
}

@keyframes rotate {
  from {
    -webkit-transform: rotate(0);
            transform: rotate(0);
  }

  to {
    -webkit-transform: rotate(360deg);
            transform: rotate(360deg);
  }
}

@-webkit-keyframes rotate {
  from {
    -webkit-transform: rotate(0);
            transform: rotate(0);
  }

  to {
    -webkit-transform: rotate(360deg);
            transform: rotate(360deg);
  }
}