Use extends

sass/components/navbar.sass

@@ -178,6 +178,8 @@ a.navbar-link
 
 .navbar-link
   padding-right: 2.5em
+  &::after
+    +arrow($navbar-dropdown-arrow)
 
 .navbar-dropdown
   font-size: 0.875rem
@@ -202,6 +204,9 @@ a.navbar-link
     .navbar-item
       align-items: center
       display: flex
+  .navbar-link
+    &::after
+      display: none
   .navbar-menu
     background-color: $navbar-background-color
     box-shadow: 0 8px 16px rgba($black, 0.1)
@@ -287,7 +292,6 @@ a.navbar-link
           transform: translateY(0)
   .navbar-link
     &::after
-      +arrow($navbar-dropdown-arrow)
       margin-top: -0.375em
       right: 1.125em
       top: 50%