PrintJS Font Size

HTML

<script src="https://printjs-4de6.kxcdn.com/print.min.js"></script>
<div id="print-area">
  <table>
    <tr>
      <th>Column 1</th>
      <th>Column 2</th>
    </tr>
    <tr>
      <td>Some Data 1</td>
      <td>More Data 1</td>
    </tr>
    <tr>
      <td>Some Data 2</td>
      <td>More Data 2</td>
    </tr>
  </table>
</div>

<button type="button" id="print-table-big">
  Print With Font Size 30px
</button>

<button type="button" id="print-table-small">
  Print With Font Size 8px
</button>

CSS

table td, table th {
  padding: 20px;
}
#print-table-big, #print-table-small {
  margin-top: 40px;
  padding: 10px;
  margin-right: 10px;
}

JavaScript

function printBig() {
  printJS({
    printable: 'print-area',
    type: 'html',
    font_size: '9px;'
  });
}

function printSmall() {
  printJS({
    printable: 'print-area',
    type: 'html',
    font_size: '9px;',
    font_family: 'verdana'
  });
}

document.getElementById ("print-table-big").addEventListener ("click", printBig);

document.getElementById ("print-table-small").addEventListener ("click", printSmall);