JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Документ без названия</title>

</head>

<body>
    <table>
        <tbody>
            <tr>
                <th>Первая ячейка</th>
                <td>4</td>
                <td>5</td>
                <td>6</td>
                <td>7</td>
            </tr>
        </tbody>
        <tbody>
            <tr>
                <th >Первая ячейка</th>
                <td>2</td>
                <td>3</td>
                <td>4</td>
                <td>5</td>
            </tr>
            <tr>
                <th>Первая ячейка</th>
                <td>2</td>
                <td>3</td>
                <td>4</td>
                <td>5</td>
            </tr>
            <tr>
                <th>Первая ячейка</th>
                <td>4</td>
                <td>5</td>
                <td>6</td>
                <td>7</td>
            </tr>
        </tbody>
    </table>
</body>
</html>

CSS

table {border-spacing: 0; border-collapse: collapse;}
th {text-align: left;}
td { border: 1px solid #000; }
tbody:after { content:''; display: table-row; height: 4px; }