table-header-group , table-footer-group properties doesn't work in Chrome
This is a known issue with Webkit, unfortunately.
Here it is on the Chrome issue tracker: http://code.google.com/p/chromium/issues/detail?id=24826
And the Webkit issue tracker: https://bugs.webkit.org/show_bug.cgi?id=17205
Star it on the Chrome issue tracker if you want to show that it is important to you (I did).