Comment by reconnecting

Thank you for asking.

XHTML Members(1):

Current websites that are valid XHTML 1.0 Strict (or Transitional)

Back to tirreno website, it is a pure transitional HTML 4.01 without JS or CSS, thus more or less same challenges to make it W3 valid (2) in our days. Have a look.

1. https://xhtml.club/members.html

2. https://validator.w3.org/check?uri=https://www.tirreno.com/&...