JSFiddle - React, Tailwind, and code Playground

HTML

<body>
	<table>
		<thead>
			<tr>
				<th>Period</th>
				<th>Position</th>
				<th>Employer</th>
			</tr>
		</thead>
		<tbody>
			<tr>
				<td>a</td>
				<td class="above">b</td>
				<td>c</td>
			</tr>
			<tr>
				<td>x</td>
                <td class="above">y</td>
				<td>z</td>
			</tr>
		</tbody>
	</table>
</body>

CSS

thead {
	display: none;
}
td {
	vertical-align: top;
}
td.above, td.above + td {
	display: block;
}