Generated by SassMeister.com.

SassMeister-input-HTML.haml

<div class="foo">foo</div>

SassMeister-input.scss

// ----
// libsass (v0.7.0)
// ----

@import "bourbon/bourbon";
@import "neat/neat";

.sidebar {
  @include span-columns(4);
}

.body {
  @include span-columns(8);
}

SassMeister-output.css

* {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box; }

.sidebar {
  float: left;
  display: block;
  margin-right: 2.35765%;
  width: 31.76157%; }
  .sidebar:last-child {
    margin-right: 0; }

.body {
  float: left;
  display: block;
  margin-right: 2.35765%;
  width: 65.88078%; }
  .body:last-child {
    margin-right: 0; }

SassMeister-rendered.html

<div class="foo">foo</div>