XSS issue in contract page

My project demo is : https://identsoft.ambitiousit.net/
And reviewer said that this is not secured. XSS problem . After said that we try to solved our all issue but reviewer said that same problem. I don’t understand this reason. I am level 4 author.
Please help me.

Hi @ambitiousitbd,

Assuming reviewer focused on sanitize your input. To keep yourself safe from XSS, you must sanitize your input. Your application code should never output data received as input directly to the browser without checking it for malicious code.

Also not only Contact page but also full of your coding should to check.

Thanks

Are you please test my web page where and how get the xss error ???