<center>
  <table style="width: 100%; max-width: 600px; padding: 20px;">
    <tr>
      <td style="background-color: #eeeeee; font-size: 14px; padding: 16px; font-family: Verdana, Geneva, sans-serif; border-radius: 25px;">
        <div id="editable">
          <h1>Hello!</h1>
          <p>Click on this text and the inline toolbar will appear.</p>
        </div>
      </td>
    </tr>
  </table>
</center>

tinymce.init({
  selector: "#editable",
  inline: true,
  toolbar: "styleselect | bold italic forecolor | removeformat",
  menubar: false
});