title: If the `li` element is a flexbox, then the bullet will not show?
body: <p>If we have an unordered list, the default is that there are bullets:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;ul&gt;
    &lt;li&gt;hello&lt;/li&gt;
    &lt;li&gt;world&lt;/li&gt;
  &lt;/ul&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>However, if we make it <code>display: flex</code>, the bullet doesn't show any more:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>li { display: flex }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;ul&gt;
    &lt;li&gt;hello&lt;/li&gt;
    &lt;li&gt;world&lt;/li&gt;
  &lt;/ul&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>Is there such a rule in CSS because it might be natural still to show the bullet but let</p>
  <pre class="lang-css prettyprint-override"><code>ul { list-style-type: none; }
  </code></pre>
  <p>to control whether to show the bullets.</p>