Themes

Given the theme CSS:

.nav-tabs > li > a {
    padding-top: 8px;
    padding-bottom: 8px;
    border: 1px solid #ddd;
    border-radius: 4px 4px 0 0;
    color: setting:maincolor;
}

.nav-tabs > li > a:hover {
    background-color: setting:maincolor !important;
    color: #fff !important;
    text-decoration: none;
}

.nav-tabs > .active > a,
.nav-tabs > .active > a:hover,
.nav-tabs > .active > a:focus {
    color: #fff !important;
    background-color: setting:maincolor;
    border-bottom-color: transparent;
    cursor: pointer;
}

.nav-tabs > .active > a:focus {
    color: setting:fontcolor !important;
}

Then the background and colour are set by the 'maincolor' setting with 'fontcolor' being used on an active state.  If this is problematic for you, then write your own custom CSS to override them.