title: summernote editor dropdown is hiding behind another editor
body: <p>Steps to reproduce:</p>
  
  <p>Go to the URL: <a href="https://summernote.org/examples/" rel="nofollow noreferrer">https://summernote.org/examples/</a></p>
  
  <p>Click on Font / Color dropdown</p>
  
  <p>It's not overlapping / hiding behind the another editor</p>
  
  <p><a href="https://i.stack.imgur.com/QlVPZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QlVPZ.png" alt="enter image description here"></a></p>
  
  <p>Any help would be appreciated.</p>