How can I change the Sub-category link in the main category page?

When I click the parent category, it brings me to the category page, displaying all the listings in that category.

If I want a particular sub category, I have to click on the respective text. The problem is that the sub categories’ text are not obvious to the user. I would like to add a border or something to make them more obvious to my users.

I am using the content-listing-business.php. I like the design but I just need to edit that portion. Any advice?