hacks-guide-minimal-mistakes-theme/_sass/vendor/font-awesome/_spinning.scss

// Spinning Icons
// --------------------------

.#{$fa-css-prefix}-spin {
  -webkit-animation: spin 2s infinite linear;
  -moz-animation: spin 2s infinite linear;
  -o-animation: spin 2s infinite linear;
  animation: spin 2s infinite linear;
}

@-moz-keyframes spin {
  0% { -moz-transform: rotate(0deg); }
  100% { -moz-transform: rotate(359deg); }
}
@-webkit-keyframes spin {
  0% { -webkit-transform: rotate(0deg); }
  100% { -webkit-transform: rotate(359deg); }
}
@-o-keyframes spin {
  0% { -o-transform: rotate(0deg); }
  100% { -o-transform: rotate(359deg); }
}
@keyframes spin {
  0% {
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }
  100% {
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}