react/packages/react-devtools-extensions/popups/disabled.html

<script src="shared.js"></script>
<style>
  html, body {
    font-size: 14px;
    min-width: 410px;
    min-height: 33px;
  }

  body {
    margin: 8px;
  }

  hr {
    width: 100%;
  }
</style>
<p>
  <b>This page doesn&rsquo;t appear to be using React.</b>
  <br />
  If this seems wrong, follow the <a href="https://github.com/facebook/react/tree/master/packages/react-devtools#the-react-tab-doesnt-show-up">troubleshooting instructions</a>.
</p>