<style type="iframe">
  @import "index";

  .link {
    @extend %click-expand-style;

    @include click-expand(20px);
  }

  /* Addon */
  .container {
    position: relative;
    padding: 40px 0;
    text-align: center;
  }

  .link {
    &:before {
      background: red;
    }
  }

  span {
    background: yellow;
  }
</style>

<div class="container">
  <a class="click-expand link" href="#">
    <span>Link</span>
  </a>
</div>
