Alternating background colors of PDF invoice items rows

If you want to have different background of invoice items rows in PDF/HTML invoices, you can use CSS to achieve that.

1. Edit your invoice template in Settings → Billing → Invoice Customization → Invoice template 
2. Click on HTML button to edit html source of your template

3. To <table> element holding your invoice items, add id attribute:

   <table id="invoice-table-items">

4. At the bottom of your template, add <style> block with css rules providing alternating backgrounds, like so:
    

   <style>
   #invoice-table-items tr:nth-child(odd) {
   	background: #c0c0c0;
   }
   #invoice-table-items tr:nth-child(even) {
   	background: #ffffff;
   }
   </style>