background-color: $shadow;
    }

    &.sw {
      background: linear-gradient(45deg, $shadow 50%, white 50%), $background;
    }

    &.ne {
      background: linear-gradient(45deg, white 50%, $shadow 50%), $background;
    }
  }
}

.back {
  background-color: white;
}

.front {
  background-color: darkgrey;
}

.left {
  background-color: lightgrey;
}

.right {
  background-color: grey;
}
            </code></pre>
          </section>
          <section>
            <iframe width="100%" height="600" data-s