public/422.html

<!DOCTYPE html>
<html>
<head>
  <title>The change you wanted was rejected (422)</title>
  <meta name="viewport" content="width=device-width,initial-scale=1">
  <style>
  body {
    background-color: #EFEFEF;
    color: #2E2F30;
    text-align: center;
    font-family: -apple-system, BedgeMacSystemFont, Segoe UI, Roboto, Droid Sans, Arial, sans-serif;
    margin: 0;
  }

  div.dialog {
    width: 95%;
    max-width: 43em;
    margin: 4em auto 0;
  }

  div.dialog > div {
    border: 1px solid #bbb;
    border-top: #B00100 solid 4px;
    background-color: white;
    padding: 2em;
  }

  h1 {
    font-size: 150%;
    color: #9C0100;
    line-height: 1.5em;
  }

  p {
    line-height: 1.5;
  }

  p.back {
    margin-top: 1.1em;
  }

  a {
    color: #1975ca;
    text-decoration: none;
  }

  a:hover {
    text-decoration: underline;
  }

  .back a {
    margin-left: -1em;
    padding: 10px 15px;
  }

  .back a:hover {
    background: #1975ca;
    color: white;
    text-decoration: none;
  }
  </style>
</head>

<body>
  <!-- This file lives in public/404.html -->
  <div class="dialog">
    <div>
      <h1>The change you wanted was rejected.</h1>
      <p>Maybe you tried to change something you didn't have access to.</p>
      <p class="back">
        <a href="/" title="Home page">&larr; Back to the home page</a>
      </p>
    </div>
  </div>
</body>
</html>