User blog comment:TOR/MediaWiki Upgrade/@comment-44061-20120703195535/@comment-2200849-20120705083626

This is due to HTML5 conformance, as noted by the developers:  &ldquo;Most presentational html attributes like valign are now converted to inline css style rules. These attributes were removed from html5 and so we clean them up when $wgHtml5 is enabled. This can be disabled using $wgCleanupPresentationalAttributes.&rdquo; Use style="margin-left: auto; margin-right: auto;" for centering things instead of align="center".