@mixin ng-if-fade($duration) {
  &.ng-enter,
  &.ng-leave {
    transition: opacity ease-in-out $duration;
  }

  &.ng-enter,
  &.ng-leave.ng-leave-active {
    opacity: 0;
  }

  &.ng-leave,
  &.ng-enter.ng-enter-active {
    opacity: 1;
  }
}