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

    # Security headers
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Permissions-Policy "camera=(), microphone=(), geolocation=()" always;

    # nginx defaults to 1m and answers anything larger with its own HTML 413
    # before the request reaches an upstream. Kept in step with the 50MB
    # per-document ceiling the API enforces (DOCUMENT_UPLOAD_MAX_BYTES).
    client_max_body_size 50m;

    gzip on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/wasm;
    gzip_min_length 1024;

    location / {
        try_files $uri $uri/ /index.html;
    }

    # Cache static assets aggressively
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff2?)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}