equivalent subcategory to .current-cat-parent

hi, i’ve been looking for the answer for days now.

i am using categories and subcategories as main menu.

when i am in a single post, i would like to show the category and subcategory. i’ve accomplished it.

now i need to change the style of the subcategory when selected (in main menu and single post), like you do with .current-cat-parent

i have my functions.php file with this code in:

[Code moderated as per the Forum Rules. Please use the pastebin]

please, if anyone could give me any type of advice, i would really appreciate it.

thanx so much for your time!