title: How do I hide the shadow under react-navigation headers?
body: <p>How do I hide the shadow under react-navigation headers?<br>
  They look like this.<br>
  <a href="https://i.stack.imgur.com/c763q.png" rel="noreferrer"><img src="https://i.stack.imgur.com/c763q.png" alt="enter image description here"></a></p>