mdb-ui-kit/scss/mixins/_navs.scss

@mixin mdb-tabs-color($color, $active-color, $active-border, $disabled-link-color, $disabled-link-hover-color) {
  .nav-link {

    color: $color;

    &.active {
      color: $active-color;
      border-color: $active-border;
      @include hover-focus {
        border-color: $active-border;
      }
    }

    // Disabled state lightens text and removes hover/tab effects
    &.disabled {
      color: $disabled-link-color;

      @include plain-hover-focus {
        color: $disabled-link-hover-color;
      }
    }
  }
}