scribe">.Arrange--middle</h2>
  <h3 class="Test-it">middle-aligns content</h3>
  <div class="Test-run">
    <div class="Arrange Arrange--middle">
      <div class="Arrange-sizeFit dev-highlight">
        <div class="fixture-Box"></div>
      </div>
      <div class="Arrange-sizeFill dev-highlight">
        <p>Main content.</p>
      </div>
    </div>
  </div>

  <h2 class="Test-describe">.Arrange--bottom</h2>
  <h3 class="Test-it">bottom-aligns content</h3>
  <div class="Test-run">
    <div class="Arrange A