remove unexisted class style

src/client/styles/scss/_navbar.scss

@@ -77,9 +77,6 @@
 }
 
 .grw-custom-navigation {
-  .default-active-tab {
-    border-bottom: 2px solid;
-  }
   .grw-nav-slide-hr {
     border-bottom: 2px solid;
     transition: 0.3s ease-in-out;