JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="tree">
    <li><span>public</span></li>
    <li><span>server.js</span></li>
    <li>
        <span>server</span>
        <ul>
            <li><span>webfs</span></li>
        </ul>
    </li>
    <li><span>specs</span></li>
    <li>
        <span>src</span>
        <ul>
            <li>
                <span>core</span>
                <ul>
                    <li><span>CellAddress.js</span></li>
                </ul>
            </li>
        </ul>
     </li>
</ul>

CSS

ul.tree {
  border-top: 1px solid grey;
}

ul.tree, ul.tree ul {
  padding: 0;
  margin: 0;
  list-style: none;
}

ul span {
    display: block;
    padding-left: 25px;
    border-bottom: 1px solid #666;
    height: 25px;
    line-height: 25px;
    background: url("http://lorempixel.com/10/8/") no-repeat scroll 5px 8px transparent;
}

ul ul span {
    padding-left: 35px;
    background-position: 15px 8px; 
}

ul ul ul span {
    padding-left: 45px;
    background-position: 25px 8px;
}