@mixin alert-variant($background, $border, $color) {
  color: darken($color, 5%);
  @include gradient-bg(darken($background, 15%));
  border-color: $border;

  hr {
    border-top-color: lighten($border, 25%);
  }

  .alert-link {
    color: lighten($color, 5%);
  }
}