position:relative specified on table elements was ignored on Firefox because the effect was “undefined” in the CSS2 spec, while it worked as “expected” on other browsers. If you’d like to have an absolutely-positoned element in the table cell, a common workaround was putting an extra, relatively-positioned
<div> element beneath
The Firefox implementation has been changed to accept
position:relative as the effect has been defined in the CSS3 spec. You may want to keep the workaround above for the backward compatibility at least until Firefox 24 ESR reaches the end of support in .
This change may potentially break pages that apply
position:relative to table elements other than
<td> while the author expects nothing to happen. The Web Console will warn such a case to make tracking down the issue easy.