Nested list sample 2

These are html tags you type.

    <ul>
      <li>
        first level
        <ul>
          <li>
            second level
            <ul>
              <li>
                third level
                <ul>
                  <li>
                    fourth level
                  </li>
                  <li>
                    fourth level
                  </li>
                </ul>
              </li>
              <li>
                third level
              </li>
            </ul>
          </li>
          <li>
            second level
          </li>
        </ul>
      </li>
      <li>
        first level
        <ul>
          <li>
            second level
          </li>
          <li>
            second level
          </li>
        </ul>
      </li>
    </ul>

Note:

1. The nested lists are all <ul> lists
2. By default the browser uses list type disc for the first level, circle for the second level, and square for the third level.
3. After the third level, the list type is stuck on square.
4. The list type does not change for nested <ol> lists