server {
    listen 80;
    listen [::]:80;
    server_name localhost;
    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 Referrer-Policy "strict-origin-when-cross-origin" always;

    # Gzip compression
    gzip on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml text/javascript image/svg+xml;
    gzip_min_length 1000;

    # Cache static assets
    location /assets/ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }

    # SPA fallback — serve index.html for all non-file routes
    location / {
        try_files $uri $uri/ /index.html;
    }
}