Make PWA standalone instead of fullscreen

Change-Id: I3c8e82974a87269f08a9b054aadafc8b525a99e8
diff --git a/manifest.json b/manifest.json
index c85442b..9314d50 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,6 +1,6 @@
 {
   "background_color": "#0043a9",
-  "display": "fullscreen",
+  "display": "standalone",
   "icons": [
     {
       "src": "img/icon.png",