JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <td>test</td> <td>test</td>
    </tr>
    <tr class="separated">
        <td>test</td> <td>test</td>
    </tr>
    <tr>
        <td>test</td> <td>test</td>
    </tr>
</table>

CSS

tr.separated td {
    /* set border style for separated rows */
    border-bottom: 1px solid black;
} 

table {
    /* make the border continuous (without gaps between columns) */
    border-collapse: collapse;
}