CODE EXAMPLE FOR HTML

Style a specific row or column of a HTML table using the css class for the table

.style tbody>:nth-child(1) {
  background: red;
}

<table class="style">
  <tbody>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>4</td>
      <td>5</td>
      <td>6</td>
    </tr>
    <tr>
      <td>7</td>
      <td>8</td>
      <td>9</td>
    </tr>
  </tbody>
</table>