diff --git a/vite.config.ts b/vite.config.ts
index 08480ed..db17707 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -61,8 +61,10 @@ export default defineConfig({
           },
         ],
         navigateFallback: "/index.html",
-        // Never let the SPA fallback swallow API calls.
-        navigateFallbackDenylist: [/^\/api/],
+        // Never let the SPA fallback swallow API calls, nor game assets:
+        // opening a rules PDF is a navigation, which would otherwise be
+        // answered with index.html instead of the file.
+        navigateFallbackDenylist: [/^\/api/, /^\/games-assets\//],
         cleanupOutdatedCaches: true,
       },
     }),