How to Change Header Icon Color?

Hey, something has changed since your suggestion. I’m not sure why but this isn’t working for me either. CSS sheet looks like this:

    .custom-header-links a:hover {
    background-color:#346A77;
    }

    .d-header-icons .d-icon {
       color: black; 
    }

    .d-header-icons .d-icon:hover {
       background-color: #346A77; 
       color: red;
    }

The icons and the hover look like this–whatever color I make the icons or the hover it doesn’t “take”:

When I inspect the element it is showing that the style is there, but it’s not cascading for some reason. Any ideas?

I have installed custom headers but that wouldn’t be changing anything would it?

Many thanks