fix height of sub navigation

apps/app/src/client/components/Navbar/GrowiContextualSubNavigation.module.scss

@@ -2,9 +2,9 @@
 @use '@growi/core-styles/scss/bootstrap/init' as bs;
 
 .grw-contextual-sub-navigation {
-  @include bs.media-breakpoint-down(md) {
-    // set min-height to keep the height
-    //  even if the item is empty on the share link page
+  min-height: 46px;
+
+  @include bs.media-breakpoint-up(lg) {
     min-height: 46px;
   }
 }