I have created a button that when you click it, it will open up a window to print a specific div (the todos div).

See images bellow:

1. The initial project

2. What do I see when I click the print button

As you can see when I click the print button, it displays only the the todos without the applied css. How can I do this?

JS for print button:

<script type="text/javascript">
    function printDiv(divName) {
        var printContents = document.getElementById(divName).innerHTML;
        w=window.open();
        w.document.write(printContents);
        w.print();
        w.close();   
    }
</script>

HTML for the print button:

<input type="button" id="print-btn" onclick="printDiv('printArea')" value="print a div!"/>