with top row headings

Header Col A Header Col B Header Col C Header Col D
Cell A1 Cell B1 Cell C1 Cell D1
Cell A2 Cell B2 Cell C2 Cell D2
Cell A3 Cell B3 Cell C3 Cell D3
Cell A4 Cell B4 Cell C4 Cell D4
<table class="data-table">
    <thead>
        <tr>
            <th scope="col">Header Col A</th>
            <th scope="col">Header Col B</th>
            <th scope="col">Header Col C</th>
            <th scope="col">Header Col D</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Cell A1</td>
            <td>Cell B1</td>
            <td>Cell C1</td>
            <td>Cell D1</td>
        </tr>
        <tr>
            <td>Cell A2</td>
            <td>Cell B2</td>
            <td>Cell C2</td>
            <td>Cell D2</td>
        </tr>
        <tr>
            <td>Cell A3</td>
            <td>Cell B3</td>
            <td>Cell C3</td>
            <td>Cell D3</td>
        </tr>
        <tr>
            <td>Cell A4</td>
            <td>Cell B4</td>
            <td>Cell C4</td>
            <td>Cell D4</td>
        </tr>
    </tbody>
</table>

top row headings and left column headings

Header Col A Header Col B Header Col C
Header Row 1 Cell A1 Cell B1 Cell C1
Header Row 2 Cell A2 Cell B2 Cell C2
Header Row 3 Cell A3 Cell B3 Cell C3
Header Row 4 Cell A4 Cell B4 Cell C4
<table class="data-table">
    <thead>
        <tr>
            <th scope="col"></th>
            <th scope="col">Header Col A</th>
            <th scope="col">Header Col B</th>
            <th scope="col">Header Col C</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <th scope="row">Header Row 1</th>
            <td>Cell A1</td>
            <td>Cell B1</td>
            <td>Cell C1</td>
        </tr>
        <tr>
            <th scope="row">Header Row 2</th>
            <td>Cell A2</td>
            <td>Cell B2</td>
            <td>Cell C2</td>
        </tr>
        <tr>
            <th scope="row">Header Row 3</th>
            <td>Cell A3</td>
            <td>Cell B3</td>
            <td>Cell C3</td>
        </tr>
        <tr>
            <th scope="row">Header Row 4</th>
            <td>Cell A4</td>
            <td>Cell B4</td>
            <td>Cell C4</td>
        </tr>
    </tbody>
</table>