JSFiddle - React, Tailwind, and code Playground

HTML

<table border="1">
  <tr>
    <td>1</td>
  </tr>
  <tr>
    <td>2</td>
  </tr>
  <tr>
    <td>3</td>
  </tr>
  <tr>
    <td>4</td>
  </tr>
</table>

CSS

table tr
{
  border:1px solid transparent;
}
table>tbody>tr:first-child
{
	border-bottom: 1px solid red;
}