The notes for the Table element clearly state <tfoot> is not supported due to the way tables are styled with Flexbox. This is an issue that is not going to be addressed as it is (as far as I can tell) impossible to make this work anyways, due to the fact that <tfoot> elements come before the <tbody> element.

Thanks for your hint.

Well, I think it is not impossible to handle the tfoot.
Initially I did a little test with flex order: https://codepen.io/anon/pen/qKgZbO and it doesn't look that bad.

This seems interesting, I'll give it a shot and report back with my results.

The main issue with tfoot is that it breaks the .horizontal table variant. I will add a note for this fix for the normal tables, as it's a one-liner for people who need it.