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

    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-eval' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; font-src 'self';";

    # Caching configuration for static assets
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
        expires 30d;
        add_header Cache-Control "public, no-transform";
    }

    # Always serve index.html for any request
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Error handling
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}