title: React-perfect-scrollbars shown despite no overflow
body: <p>I'm having trouble getting React Perfect Scrollbar working within AntD modal windows.</p>
  <p>Specifically, there's a strange bug that causes the modal to open with both scrollbars displayed when they shouldn't be. The size of the scrollbars indicates a huge amount of content whereas the <em>actual</em> content fits easily within the parent div and therefore the scrollbars should be hidden. As soon as one clicks on either the horizontal or vertical scrollbar, or uses the mouse wheel, they disappear.</p>
  <p><a href="https://i.stack.imgur.com/3UpT7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3UpT7.png" alt="enter image description here" /></a></p>
  <p>I have tried to extract the code and reproduce this but the bug doesn't seem to manifest in my Stackblitz snippet. Nevertheless, I include it here on the off-chance that the problem is apparent despite this.</p>
  <p><a href="https://stackblitz.com/edit/react-g4ugrl?devtoolsheight=33&amp;file=src/BaseModal.js" rel="nofollow noreferrer">https://stackblitz.com/edit/react-g4ugrl?devtoolsheight=33&amp;file=src/BaseModal.js</a></p>
  <p>Any ideas?</p>
  <p>Thanks</p>