<style>
ol { counter-reset: item !important; }
li{ display: block !important; }
li:before {
    content: counters(item, ".") " " !important;
    counter-increment: item !important;
}
</style>

<ol>
    <li>First</li>
    <li>Second
    <ol>
        <li>Second Dot One</li>
        <li>Second Dot Two</li>
    </ol>
    </li>
</ol>

<p>test sentence.</p>

<ol start="12">
    <li>&nbsp;It must start from 12 not 1</li>
</ol>