CSS for red background image no longer matches

I haven't investigated this very far to see when/if this changed or what else is going on here. But we've been seeing that the background image maple leaf has stopped showing up on the pop-up page for view contribution (on the contact page).

The code in civicrm_cdntaxreceipts.css is using class ui-icon-check, however the site itself appears to have these classes on this span element: ui-button-icon ui-icon fa-check.

So changing the text in that css file from .ui-icon-check to .ui-icon.fa-check worked for us, lines 14 and 35.