w3 html Validation error

Your Plug-in is getting w3 validation error on Faq Page.

http://desango.com/clients/dnaforensics/faq/

Please check error:
https://validator.w3.org/nu/?doc=http%3A%2F%2Fdesango.com%2Fclients%2Fdnaforensics%2Ffaq%2F

https://ww.wp.xz.cn/plugins/accordions/