title: How do I implement field validation for 'react-select'
body: <p>I need a simple "required" validation for 'react-select' (<a href="https://github.com/JedWatson/react-select" rel="nofollow noreferrer">github repo</a>).
  In the latest version it uses css-in-js approach. So I have custom styles:</p>
  
  <pre><code>export const customStyles = {
  
  
   control: (base, state) =&gt; ({
          ...base,
      }),
  
      menu: (base, state) =&gt; ({
          ...base,
      }),
  
      menuList: (base, state) =&gt; ({
          ...base,
      }),
  }
  </code></pre>
  
  <p>How can I change e.g. <code>borderColor</code> if field is invalid?</p>