Change "Menu | Active Link color" depending on the menu item via CSS

Hi there,

I am wondering about the "Active Link color" of the Main Menu.

One can adjust the Active Link color here: Design / BeTheme Options / Colors / Menu & Action Bar > Menu | Active Link color

In the description next to this field it says "This is also Active Link Border".

How can i overrule this setting via CSS?

I have a main menu with 3 menu items, each of them should have a different border-bottom - i was able to do this via style.css in the child-theme FOR THE "NORMAL" MENU STATUS (not sticky), i give you just an excerpt:

#menu-item-61 a, #menu-item-61 a:hover {
border-bottom-color: #ed1f5e;
}

It works well - but when i scroll down and the sticky header comes up - the menu items color is the color defined in the BeTheme option described above. Also there is a border-bottom for the active link.
Where is it defined??

Best regards and thank you for your kind response,
Markus

PS
I use Classic Header.
WordPress 4.4.2
BethemeVersion: 11.7