Why do the OpenBSD web pages not conform to HTML4/XHTML?
The present web pages have been carefully crafted to work on a wide variety of actual browsers going back to browser versions 4.0 and later. We do not want to make these older pages conform to HTML4 or XHTML until we’re sure that they will also work with older browsers; it’s just not a priority. We welcome new contributors, but suggest you work on writing code, or on documenting new aspects of the system, not on tweaking the existing web pages to conform to newer standards.