server {
    listen 80;
    server_name _; # Listen for any server name

    root /usr/share/nginx/html;
    index index.html index.htm;

    # Security Headers
    # Content Security Policy (CSP) - Prevents XSS attacks
    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; font-src 'self'; connect-src 'self'; frame-ancestors 'none';" always;
    
    # Strict Transport Security (HSTS) - Forces HTTPS
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
    
    # X-Frame-Options - Prevents clickjacking
    add_header X-Frame-Options "DENY" always;
    
    # X-Content-Type-Options - Prevents MIME type sniffing
    add_header X-Content-Type-Options "nosniff" always;
    
    # Referrer Policy - Controls referrer information
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    
    # X-XSS-Protection - Additional XSS protection (legacy but still useful)
    add_header X-XSS-Protection "1; mode=block" always;
    
    # Permissions Policy - Controls browser features
    add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;

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

    # Optional: You can add custom error pages if you create them in your 'static' folder
    # error_page 404 /404.html;
    # location = /404.html {
    #     internal;
    # }
}