crosstab help

Hi All,

I have a cross tab report having columns as brand and rows as location.

For every  Brand I have summary fields like sales,cost,variance.

It is like this

                                 Brand1                                        Brand2                                 Brand3

Location 1         sales        Cost       Var                 sales      Cost      Var            sales     Cost       Var   

Now I need change the background color of   sales        Cost       Var    headers  alternately.

Please help