title: How to get all child views to overlap and fill their parent w/ React Native Flexbox
body: <p>I want to have all children filling the available space, and overlapping one another, so only the last child is visible.</p>
  
  <pre><code>&lt;View style={???}&gt;
    &lt;View style={???} /&gt; // Not visible (if bg color set on next child)
    &lt;View style={???} /&gt;
  &lt;/View&gt;
  </code></pre>
  
  <p>I've tried various combinations of <code>flex</code>, <code>position</code>, <code>alignSelf: stretch</code>, etc., and can't find a winning combo.   </p>