server {
    listen 80;
    server_name _;
    root /usr/share/nginx/html;
    index index.html;

    # serve config.json with correct MIME type + CORS for fetch()
    location = /config.json {
        add_header Content-Type application/json;
        add_header Access-Control-Allow-Origin *;
    }

    # SPA fallback (not needed for static, but safe to have)
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Security headers
    add_header X-Frame-Options SAMEORIGIN;
    add_header X-Content-Type-Options nosniff;
    add_header Referrer-Policy no-referrer-when-downgrade;

    gzip on;
    gzip_types text/html text/css application/javascript application/json image/svg+xml;
}