JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="foo">foo</div>
  <div class="foo">foo</div>
  <div class="foo">foo</div>
</div>

<div class="container">
  <div class="foo">foo</div>
  <div class="foo">foo</div>
  <div class="foo">foo</div>
  <button type="button">load more</button>
</div>

CSS

.container {
  padding: 5px;
  margin-bottom: 1em;
  border: 1px dotted blue;
}

.foo + .foo {
  border-top: 1px solid red;
}