JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="item">
    itemA
  </div>
  <div class="item">
    itemBitemB
  </div>
  <div class="item">
    itemCCCC
  </div>
  <div class="item">
    itemA
  </div>
  <div class="item">
    itemBitemB
  </div>
  <div class="item">
    itemCCCC
  </div>
  <div class="item">
    itemA
  </div>
  <div class="item">
    itemBitemB
  </div>
  <div class="item">
    itemCCCC
  </div>
</div>

CSS

.container {
  display: flex;
  flex-wrap: wrap;
  border: 1px solid #ccc;
  border-bottom: 0;
  
  max-width: 470px; /* for the sake of example */
}

.item {
  display: inline-flex;
  padding: 10px;
  border-bottom: 1px solid #ccc;
}