CSS Fix for Responsive

First of all, thanks for the amazing plugin! It’s great and I’ve already given it a 5 star review.

I’m having a problem with mobile styling and I want to hide the “product name” on mobile devices only. I added the following css but it didn’t hide the element:

@media only screen and (max-width: 640px)
.tinv-wishlist table.tinvwl-table-manage-list thead th.product-name, .tinv-wishlist table.tinvwl-table-manage-lists thead th.wishlist-name {
display: none;
}

I can hide the “product name” altogether with this code, but I want it to be visible on non-mobile devices:

.tinv-wishlist table.tinvwl-table-manage-list thead th.product-name, .tinv-wishlist table.tinvwl-table-manage-lists thead th.wishlist-name {
display: none;
}

Can you please tell me what I’m doing wrong with my @media css?

Thanks!