<ol>
  <li>one
    <ol>
      <li>one.one</li>
    </ol>
  </li>
  <li>two
    <ol>
      <li>two.one
        <ol>
          <li>two.one.one</li>
        </ol>
      </li>
      <li>two.two
        <ul>
          <li>bullet</li>
        </ul>
        <ol>
          <li>two.two.one</li>
        </ol>
      </li>
    </ol>
  </li>
</ol>
ol {
  counter-reset: item;
  list-style-type: none;
}
ol>li { 
  counter-increment: item;
}
ol>li::before { 
  content: counters(item, '.') ' - '; 
}

External CSS

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External JavaScript

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