How to add line between row 1 and row 2 in sales invoice

[Mabaega]

Use footer, you can insert into existing footer or create new footer

<div id='line-border' style='display: none;'>
<script>
document.addEventListener('DOMContentLoaded', function() {
    const printableContent = document.getElementById('printable-content');
    if (printableContent) {
        const table = printableContent.querySelector('table');
        if (table) {
            const tbodies = table.querySelectorAll('tbody');
            tbodies.forEach(tbody => {
                const tds = tbody.querySelectorAll('td');
                tds.forEach(td => {
                    if (td.className && td.className.trim() !== '') {
                        td.style.borderTop = '1px solid black';
                    }
                });
            });
        }
    }
    const selfDeletingContainer = document.getElementById('line-border');
            if (selfDeletingContainer) {
                selfDeletingContainer.remove();
            }
});
</script>
</div>