title: Override Mui theme nested in theme.breakpoints.up("md")
body: <p><strong>Code</strong></p>
  
  <pre><code>MuiTab: {
      root: {
          height: 140,
          [theme.breakpoints.up("md")]: {
               minWidth: 72,
          }
      }
  }
  </code></pre>
  
  <p><strong>Error</strong></p>
  
  <blockquote>
    <p>[ts] Cannot find name 'theme'.</p>
  </blockquote>
  
  <p><strong>Problem</strong></p>
  
  <p>I don't know where to declare "theme".</p>