This is an interesting topic. A WordPress/WooCommerce client could not add CSS via the usual way. In fact, Gravity Forms plugin (and in particular the “directory” extension), stores entries in the database BUT the directory page and the entries filtered list have the same classes, ids, and cannot be “targeted” with CSS.
Long story short, and Gravity Form or not Gravity Form, here’s the snippet you can use to add CSS to any WordPress page as long as you know its URL.
PHP Snippet: Apply CSS to a Page URL That Contains “string”
You can place PHP snippets at the bottom of your child theme functions.php file (delete "?>" if you have it there). CSS, on the other hand, goes in your child theme style.css file. Make sure you know what you are doing when editing such files - if you need more guidance, please take a look at my free video tutorial "Where to Place WooCommerce Customization?"
Does this snippet (still) work?
Please let me know in the comments if everything worked as expected. I would be happy to revise the snippet if you report otherwise (please provide screenshots). I have tested this code with Storefront theme, the WooCommerce version listed above and a WordPress-friendly hosting on PHP 7.3.
Check out these free video tutorials. You can learn how to customize WooCommerce without unnecessary plugins, how to properly configure the WooCommerce plugin settings and even how to master WooCommerce troubleshooting in case of a bug!
Business Bloomer Founder
Author, WooCommerce expert and WordCamp speaker, Rodolfo has worked as an independent WooCommerce freelancer since 2011. His goal is to help entrepreneurs and developers overcome their WooCommerce nightmares. Rodolfo loves travelling, chasing tennis & soccer balls and, of course, wood fired oven pizza.