複数列レイアウトでリスト項目が列をまたいで分割されないようにするにはどうすればよいですか?

.x li {
    break-inside: avoid-column;
}

<div class='x'>
    <table>
        <tr><td>Number one</td></tr>
        <tr><td>Number two (longer)</td></tr>
        <tr><td>Number three</td></tr>
    </table>
</div>

.x {
    column-count: 3;
    width: 30em;
}

.x ul {
    margin: 0;
}

.x li {
    -webkit-column-break-inside: avoid;
    -moz-column-break-inside:avoid;
    -moz-page-break-inside:avoid;
    page-break-inside: avoid;
    break-inside: avoid-column;
}

<div class='x'>
    <ul>
        <li>Number one, one, one, one, one</li>
        <li>Number two, two, two, two, two, two, two, two, two, two, two, two</li>
        <li>Number three</li>
    </ul>
</div>