<ul dir="auto">
<li>[ x] I have searched the <a href="https://github.com/mui-org/material-ui/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<p dir="auto">This isn't an issue with the project.</p>
<p dir="auto"><a href="https://codesandbox.io/s/23qv662q00" rel="nofollow">This CodeSandBox</a> linked to in <a href="https://material-ui-next.com/customization/themes/" rel="nofollow">this doc page</a> is missing the <a href="https://github.com/mui-org/material-ui/blob/v1-beta/docs/src/pages/customization/WithTheme.js">WithTheme.js</a> file.</p>
<p dir="auto">I don't know how (or if it's possible) to PR from CodeSandBox. <a href="https://codesandbox.io/s/w0x52r6kol" rel="nofollow">Here's a fork</a>.</p>
<p dir="auto">Thanks</p>
<h3 dir="auto">Problem description</h3>
<p dir="auto">When using this with react-starter-kit it generates warnng:<br>
<code class="notranslate">(program):44 Warning: React attempted to reuse markup in a container but the checksum was invalid. This generally means that you are using server rendering and the markup generated on the server was not what the client was expecting. React injected new markup to compensate which works but you have lost many of the benefits of server rendering. Instead, figure out why the markup being generated is different on the client or server: (client) ;width:100%;display:flex;padding-left:24 (server) ;width:100%;display:-webkit-box,-moz-box</code></p>
<p dir="auto">I've looked at other related issues and know this has been a reoccuring theme. It seems that everywhere the process.env.NODE_ENV is set the same.</p>
<h3 dir="auto">Steps to reproduce</h3>
<p dir="auto">Open an instance with chrome (v. 50) using react-starter-kit as boilerplate.</p>
<h3 dir="auto">Versions</h3>
<ul dir="auto">
<li>Material-UI:  0.15.0 and ^0.15.0-beta.2</li>
<li>React: 15.1.0</li>
<li>Browser:  Chrome 50.0.2661.102 (64-bit)</li>
</ul>