fix(css): hide the nav when the content has not yet been loaded

Author: QingWei-Li

src/themes/basic/_layout.css

@@ -10,7 +10,7 @@
 body:not(.ready) {
   overflow: hidden;
 
-  [data-cloak], .app-nav {
+  [data-cloak], .app-nav, > nav {
     display: none;
   }
 }
@@ -244,7 +244,7 @@ main {
       position: static;
     }
   }
-  
+
   .sidebar-nav {
     line-height: 2em;
   }