[Font Awesome :after mixin] #sass

_mixins.scss

// Custom Font Awesome :after
@mixin font-awesome-after($fa-icon, $margin: 5px) {
  &:after {
    font-family: FontAwesome;
    font-weight: normal;
    font-style: normal;
    display: inline-block;
    content: $fa-icon;
    text-decoration: inherit;
    position: relative;
    margin-left: $margin;
  }
}

_style.scss

// Usage:
@include font-awesome-after($fa-var-angle-double-right);
@include font-awesome-after($fa-var-angle-double-right, 8px);