Updated the styling for shoveling coal message on donate page.

This styling is for the overlay on the donate page while waiting
for the payment processor.

Issue #48515

lego @ 7eaaf3ca

-Subproject commit 4ff73f56641711a78c95921c40feeaa6a32839b8
+Subproject commit 7eaaf3cae38ac55dd3c19657491acfd96f6b3b15