discourse/app/assets/stylesheets/vendor/font_awesome/_spinning.scss

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

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

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