Add focus state to navigation link items

Nested submenu items didn't have visual indication for
focus state. Adding styles needed to meet accessiblity
guidelines.

Signed-off-by: Yoshie Muranaka <yoshiemuranaka@gmail.com>
Change-Id: I2c79e2c36a0de8d6ae27e0388c1241868172b9cd
diff --git a/src/components/AppNavigation/AppNavigation.vue b/src/components/AppNavigation/AppNavigation.vue
index 47609d9..2fc1222 100644
--- a/src/components/AppNavigation/AppNavigation.vue
+++ b/src/components/AppNavigation/AppNavigation.vue
@@ -117,10 +117,6 @@
       transform: rotate(180deg);
     }
   }
-
-  &:focus {
-    box-shadow: $btn-focus-box-shadow;
-  }
 }
 
 .icon-expand {
@@ -139,6 +135,10 @@
   &:hover {
     background-color: $gray-300;
   }
+
+  &:focus {
+    box-shadow: $btn-focus-box-shadow;
+  }
 }
 
 .nav-link--current {