bootstrap.html

<form
  class="form-inline"
  action="VALUE FROM MAILCHIP CODE"
  method="post"
  id="mc-embedded-subscribe-form"
  name="mc-embedded-subscribe-form"
  target="_blank"
>
  <div class="container">
    <div class="row sm-100 justify-content-md-center">
      <label
        for="mce-EMAIL"
        class="col-sm-2 col-form-label"
      >Email</label>
      <input
        type="email"
        name="EMAIL"
        id="mce-EMAIL"
        required=""
        class="col-sm-6 form-control"
        value="">
      <button
        class="btn btn-primary col-sm-2"
        type="submit">Join</button>
    </div>
    <input
      type="hidden"
      name="VALUE FROM MAILCHIMP CODE"
      tabindex="-1"
      value="true">
  </div>
</form>