JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

div.topic {
 border-bottom: 1px solid black;
}
div.topic:last-child {
 border-bottom: none;
}