Sections are now collapsible panels.

All sections may be expanded/collapsed at once (buttons).

Panels take colour depending on status (ok, warning, error).

Progress adding the complete wording of rules (but not yet).

W3C now in negative colours (but it's aliased).

Temporarily using just one wording for all rules.

Fixed typo in META HTTP header.

Minor CSS fixes.
2nd-level messages (info, warning, error) now displayed on collapsible panels, too.
Detailed wording now displayed as <blockquote>'s.