JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <th>1</th>
        <th>2</th>
    </tr>
    <tr>
        <td>3</td>
        <td>4</td>
    </tr>
    <tr>
        <td>5</td>
        <td>6</td>
    </tr>
</table>

CSS

body { background: #ccc; }

table { border-spacing: 0; border-collapse: separate; border-bottom: 1px solid #888; }

th, td { border-bottom: 1px solid #fff; padding: 0 3em; }

td { border-top: 1px solid #888; }