proper cross-browser CSS to set font-size of grid column headers

[Tim R]

.k-grid-header {font-size: x-small !important;}

works fine in IE but I'm not having any success with Chrome, FF, or Opera.  What is the proper cross-browser CSS to set the font-size of the header?

Thanks

[Tim R]

Got it: .k-grid-header-wrap th {font-size: x-small !important; }