@include linear-gradient(red, blue);
  
  /*Converts px value to em*/
  font-size: em(15);

  /*Values: Size, Color, Direction*/
  @include triangle (20px, red, up-left);

<section class="row">
<aside class="col-md-4"></aside>
<article class="col-md-8"></article>
</section>

<section>
<aside></aside>
<article></article>
</section>

 section{
    @include outer-container(1200px);
    aside{
      @include span-columns(4);
    }
    article{
      @include span-columns(8);
    }
  }