popup.html

<!DOCTYPE html>
<html>
  <head>
    <style>
      body {
        width: 400px;
      }
      header {
        display: flex;
        align-items: center;
        justify-content: space-between;
      }
      h1 {
        font-size: 1.2rem;
        margin: 0 0 0.5rem;
      }
      input {
        width: 20rem;
      }
      #errors {
        color: firebrick;
      }
      #warnings {
        color: orange;
      }
    </style>
  </head>
  <body>
    <header>
      <h1>Github Easy PR</h1>
      <a href="https://github.com/settings/tokens" target="_blank">Create token</a>
    </header>
    <div>
      <input id="token" placeholder="Set your github token" />
      <button>Save</button>
    </div>
    <div id="errors"></div>
    <div id="warnings"></div>
  </body>
  <script type="module" src="./popup.js"></script>
</html>