I am also trying to change the size of my product titles on the category page but the above changes are not working as pasted. It looks to be an H2 and I tried adjusting this in the code but still the same size.
>>
.woocommerce ul.products li.product h3 {
font-size: 25px;
}
<<
here is an example of one of my pages:
https://www.qa-bio.com/product-category/exoglycosidases/