Supreme Directory: How can I add a color to active links in the navi?

Hello guys I am just working on the CSS styles of the Supreme Directory Theme and I an having adding a special color to an active link in the top navi / primary navigation.

When I hover the links I see the color that I have set before, so this works:

/* HEADER - NAVI-LINKS, Linkfarben HOVER */
.sd #primary-nav ul li a:hover {
    color: #ed184a;
}

So I thought this should work, too – but it doesn`t:

/* HEADER - NAVI-LINKS, Linkfarben AKTIV */
.sd #primary-nav ul li a:active {
    color: #ed184a;
}

I will add login data in the next post.
Thank you in advance!