<ul>
  <li>내용1
    <ul>
      <li>내용1-1</li>
      <li>내용1-2</li>
    </ul>
  </li>
  <li>내용2
    <ul>
      <li>내용2-1</li>
      <li>내용2-2</li>
    </ul>
  </li>
  <li>내용3
    <ul>
      <li>내용3-1</li>
      <li>내용3-2</li>
    </ul>
  </li>
</ul>
ul {
  counter-reset: section;
}

li {
  list-style: none;
}

li::before {
  counter-increment: section;
  content: counters(section, ".") " "
}
li li::before {
  content: counters(section, ".", lower-roman) " "
}

External CSS

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External JavaScript

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