I think that being able to make user stylesheets based not only on HTML but also on ARIA attributes and on existing CSS commands, might be helpful, to compensate for the problems. User settings could also be used to e.g. override (and/or disable) the meaning of specific CSS commands in the styles specified in the document, and to override the results of media queries. It could also perhaps help to make the rendering more efficient if inefficient commands are disabled by the user (I often find it slow due to inefficient use of CSS commands).