JSFiddle - React, Tailwind, and code Playground

HTML

<div id="list">
<div class="topic">Some content</div>
<div class="topic">Some content</div>
<div class="topic">Some content</div>
</div>
<div class="action">Some other content</div>

CSS

#list .topic {
 border-bottom: 1px solid black;
}

#list .topic:last-child {
 border-bottom: none;
}