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

    # caption.ninja links omit the extension (e.g. /overlay?room=...).
    location / {
        try_files $uri $uri.html $uri/ =404;
    }

    # Room tokens can arrive in query strings on some pages; keep them out of logs.
    access_log off;
}