Change background and font for first row only?

Hi, 

Have a tablix in SSRS (2008R2) and would like to change the background colour and font for the first row only, is this possible and if so how would I achieve this? 

I have followed and example on setting alternate row background colour in the properties but can't see how to do this for just the first row. 

=IIF(RowNumber(Nothing) MOD 2,”LightGrey”, “LightBlue”)

Thanks