Hopeful to fix problem with .blockUI.blockOverlay of external plugin.

It seems WooCommerce support don't reply in less than 12 days or so (which is how long my last ticket has been waiting). So I am asking WPMUDEV if they have a quickie solution.

It looks like WooCommerce is using their own jQuery without properly compensating for WP's; and it is causing a blockUI block Overlay on Checkout page.

I found some information to fix this issue by adding some custom.css to the child theme but I am not sure how to do this. Is there a way to add this to a function (which I am able to implement)?

The code they used was:

/* Fix issues with jquery overlay blocking checkout button */
.woocommerce .blockUI.blockOverlay {
position: relative!important;
display: none!important;

Or- if you believe this may be a bad idea, please let me know. Thank you kindly.