Rename index.html to background.html; configure nginx to serve it as index

default.conf

@@ -2,7 +2,7 @@ server {
     listen 58881 default_server;
     server_name localhost;
     root /usr/share/nginx/html;
-    index index.html;
+    index background.html;
 
     location / {
         try_files $uri $uri/ =404;