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

/* EXTRAS
 * -------------------------- */

/* Stacked and layered icon */
@include icon-stack();

/* Animated rotating icon */
.icon-spin {
  display: inline-block;
  -moz-animation: spin 2s infinite linear;
  -o-animation: spin 2s infinite linear;
  -webkit-animation: spin 2s infinite linear;
  animation: spin 2s infinite linear;
}

/* Prevent stack and spinners from being taken inline when inside a link */
a .icon-stack,
a .icon-spin {
  display: inline-block;
  text-decoration: none;
}

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

/* Icon rotations and mirroring */
.icon-rotate-90:before {
  -webkit-transform: rotate(90deg);
  -moz-transform: rotate(90deg);
  -ms-transform: rotate(90deg);
  -o-transform: rotate(90deg);
  transform: rotate(90deg);
  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=1);
}

.icon-rotate-180:before {
  -webkit-transform: rotate(180deg);
  -moz-transform: rotate(180deg);
  -ms-transform: rotate(180deg);
  -o-transform: rotate(180deg);
  transform: rotate(180deg);
  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=2);
}

.icon-rotate-270:before {
  -webkit-transform: rotate(270deg);
  -moz-transform: rotate(270deg);
  -ms-transform: rotate(270deg);
  -o-transform: rotate(270deg);
  transform: rotate(270deg);
  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=3);
}

.icon-flip-horizontal:before {
  -webkit-transform: scale(-1, 1);
  -moz-transform: scale(-1, 1);
  -ms-transform: scale(-1, 1);
  -o-transform: scale(-1, 1);
  transform: scale(-1, 1);
}

.icon-flip-vertical:before {
  -webkit-transform: scale(1, -1);
  -moz-transform: scale(1, -1);
  -ms-transform: scale(1, -1);
  -o-transform: scale(1, -1);
  transform: scale(1, -1);
}

/* ensure rotation occurs inside anchor tags */
a {
  .icon-rotate-90, .icon-rotate-180, .icon-rotate-270, .icon-flip-horizontal, .icon-flip-vertical {
    &:before { display: inline-block; }
  }
}