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How to define a color of category as menu item when current post use it

I am working on custom theme for Wordpress, and I found a little problem. I can't figure how to style menu element to work as I want. Let's say I have a post sorted in one category. That category is listed in menu. I want to set this category as menu item as active element, so it need to change its color ...

(e.g #3498db).

I hope that everyone gets the point of my question, Thanks.