以类似树的行式显示html列表

I have a list

我有一份清单

<ul>
 <li> first article </li>
 <li> second article</li>
 <ul>
    <li> replies to second</li>
    <li> different reply to second</li>
 </ul>
 <li> third article</li>
 <ul>
    <li> reply to third</li>
    <ul>
        <li> reply to the reply</li>
    </ul>
 </ul>
</ul>
<ul>
 <li> first artic