Hello,
I try to change the color in the top main menu.First I tried to find it in the layout settings and then I put

.uk-navbar.uk-active a {
color: #44d2fd !important;
}

in the custom css. But I'm not sure, if the custom css is loaded.
I use the green template.

I also tried

.uk-navbar-nav > li.uk-active > a {
background-color: rgba(79, 150, 229, 0);
color: #659f13;
}

but that doesn't work either.

Many greetings
Judith

Problem solved.