Changing styles based on category

What I am attempting to do is add an if statement to check the category of the product, then change the border color around it based on the category.

I do not know what command to use to get the category though?

if($product_category == “143”){do this};

I dont know what I need to do to set the correct variable into the $product_category…..

I will have 3 main categories that my products fall into. They are the main parents to many sub categories.

TLDR; What function or existing variable can I use to know my products category?

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