diff --git a/agaric/sass/agaric/_component.navbar.scss b/agaric/sass/agaric/_component.navbar.scss
index cbb9207..ac5237c 100644
--- a/agaric/sass/agaric/_component.navbar.scss
+++ b/agaric/sass/agaric/_component.navbar.scss
@@ -227,6 +227,18 @@ a.navbar-link.is-active {
   }
 }
 
+// Keep underline visible when dark navbar not followed by dark section.
+.dark-header {
+  a.navbar-item.is-active,
+  a.navbar-link.is-active {
+    @include tablet {
+      &::before {
+        border-top-color: $dark;
+      }
+    }
+  }
+}
+
 .navbar-item.has-dropdown:hover .navbar-link,
 .navbar-item.has-dropdown:focus .navbar-link,
 .navbar-item.has-dropdown.is-active .navbar-link {