fix(theme): navbar menu may exceed the screen (#988) (#989)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

src/client/theme-default/components/VPMenu.vue

@@ -29,6 +29,14 @@ defineProps<{
   background-color: var(--vp-c-bg);
   box-shadow: var(--vp-shadow-3);
   transition: background-color 0.5s;
+  max-height: calc(100vh - var(--vp-nav-height-mobile));
+  overflow-y: auto;
+}
+
+@media (min-width: 960px) {
+  .VPMenu {
+    max-height: calc(100vh - var(--vp-nav-height-desktop));
+  }
 }
 
 .dark .VPMenu {