Oldschool method is to align the button

by Anatoly Kulikov

HTML

<table>
  <tr>
    <td></td>
    <td>
      <button>Кнопка</button>
     </td>
    <td></td>
  </tr>
</table>

CSS

table {
  width: 100%;
}
tr > td {
  width: 33.33%;
}
button {
  width: 100%;
}