Beta Update - Request for (more) Testing

https://beta.undeadly.org/ has received an update. The most significant changes include:

• The site has been given a less antiquated "look".(As the topic icons have been eliminated, we are no longer seeking help with those graphics.)
• The site now uses a moderate amount of semantic HTML5.
• Several bugs in the HTML fragment validator (used for submissions and comments) have been fixed.
• To avoid generating invalid HTML, submission content which fails validation is no longer displayed in submission/comment previews.
• Plain text submissions are converted to HTML in a more useful fashion.(Instead of just converting each EOL to <br>, the converter now generates proper paragraphs and interprets two or more consecutive EOLs as indicating a paragraph break.)

The redevelopment remains a work-in-progress.Many thanks to those who have contributed!

As before, constructive feedback would be appreciated.Of particular interest are reports of bugs in behaviour (for example, in the HTML validator or in authentication) that would preclude the adoption of the current code for the main site.