fix: prevent missing CSS assets from falling through to CakePHP

Author: BytesUnlimited-net

core/files/etc/nginx/includes/misp

@@ -16,6 +16,10 @@ add_header X-Robots-Tag "none" always;
 fastcgi_hide_header X-Powered-By;
 server_tokens off;
 
+location ^~ /css/ {
+    try_files $uri =404;
+}
+
 location / {
     try_files $uri $uri/ /index.php$is_args$query_string;
 }