Update manifest.json (codesandbox#1633)

Fix Top-bar color when in standalone mode.

Author: lifeiscontent

packages/app/public/manifest.json

@@ -38,5 +38,5 @@
   "scope": "/s/",
   "display": "standalone",
   "background_color": "#1C2022",
-  "theme_color": "#6CAEDD"
+  "theme_color": "#1C2022"
 }