JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
</ul>

CSS

ul {
  display: block;
  width: 100%;
  margin: 0;
  padding: 0
}

li {
  display: block;
  width: 33%;
  height: 120px;
  float: left;
  margin: 0;
  padding: 0;
  border-bottom: #666 1px solid;
  background: #fcc
}

li:nth-last-child(3),
li:nth-last-child(2),
li:last-child {
  border-bottom: 0px
}