About Grid :How to change font family and font size of a wh

I am using dhtmlGrid,now I have a question about font family of column:

I want to set a column’s font,the cells belongs to this column have the same font family, and it is different from other columns .but now I could not find how to do that.all cases is below :

1),the grid is loaded from a xml named A.xml .at this case ,how should I do?

2).the grid is iterated in the jsp file,how should I do ?

There are two ways
a) define cpecific style in XML

.my_column{ … }

in XML

b) do the same but in js code

return true;