Inconsistent treatment of color in CSS and in unlabeled PNGs

XHTML tables without tbody are broken. The XHTML Basic DTD doesn’t allow tbody. (With HTML the parser is expected to infer the tbody element if the tags are missing, but with XHTML the CSS formatter is expected to generate an anonymous table-row-group.)

No UI for link navigation. (This is not entirely an UI issue.)

BiDi problems: parentheses wrong, bad font variation, broken selection, bad ordering.

If an unrecognized font-family is set, the font gets stuck to Helvetica and can’t even explicitly be reverted to the font-family of the containing block using inherit. This means that font-family can’t be used for a screen-media-only adaptation of the Tantek hack.

No display of the title attribute.

Can’t see the engine state as with Venkman and DOM Inspector. Can’t see JS errors, because there’s no JS console.

Clicking labels of radio buttons or checkboxes doesn’t change the state of the checkboxes or radio buttons.

list-item-position: inside renders badly.

Doesn’t support the gzip encoding on HTTP.