Try it Editor: html5

Edit This Code :



<!DOCTYPE html>
<html>
<head>
<style>
table, th, td {
    border: 1px solid black;
}
</style>
</head>
<body>

<p><b>Note:</b> The dialog tag is not supported in Edge/Internet Explorer.</p>

<table>
  <tr>
    <th>January <dialog open>This is an open dialog window</dialog></th>
    <th>February</th>
    <th>March</th>
  </tr>
  <tr>
    <td>31</td>
    <td>28</td>
    <td>31</td>
  </tr>
</table>

</body>
</html>

Result :

html5_dialog