$nav-tabs-border-color;\n\n  .nav-link {\n    border-bottom-left-radius: $nav-tabs-border-radius;\n    border-top-right-radius: 0;\n    margin-right: -$nav-tabs-border-width;\n\n    @include hover-focus () {\n      border-color: $gray-200 transparent $gray-200 $gray-200;\n    }\n  }\n\n  .nav-link.active,\n  .nav-item.show .nav-link {\n    border-color: $gray-300 transparent $gray-300 $gray-300;\n  }\n\n  &.nav-tabs-right {\n    border-left: $nav-tabs-border-width solid $nav-tabs-border-color;\n   ...