Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="OuterClass">
  <div class="OuterClass-innerClass">
    First
  </div>
</div>

SassMeister-input.scss

// ----
// Sass (v3.4.14)
// Compass (v1.0.3)
// Susy (v2.2.5)
// ----

@import "susy";

$susy: (
  global-box-sizing: border-box,
  columns: 12
);

.OuterClass {
  @include container;
  background-color: blue;
  &-innerClass {
    @include span(6);
    background-color: yellow;
  }
}

SassMeister-output.css

.OuterClass {
  max-width: 100%;
  margin-left: auto;
  margin-right: auto;
  background-color: blue;
}
.OuterClass:after {
  content: " ";
  display: block;
  clear: both;
}
.OuterClass-innerClass {
  width: 49.15254%;
  float: left;
  margin-right: 1.69492%;
  background-color: yellow;
}

SassMeister-rendered.html

<div class="OuterClass">
  <div class="OuterClass-innerClass">
    First
  </div>
</div>