Export Grid to Excel using ASP.NET text color always black

I’m trying to export a grid that has 3 rows. Two of the rows have black text, and one row has blue text.
I’m calling the toExcel() function using the “full_color” parameter: grid.toExcel(“Generate.ashx”, “full_color”);
The Excel document is always created with only black text. Any idea why?

Any reponse?