.NET changing the font of the text in a DataGridView

You can create an element in your CSS with the font properties (including the size) and then reference the element in the DataGridView control (using the CssClass property).

Unless I misunderstand your question, all you would need to do is:

<asp:GridView ID="gridview1" runat="server" font-size="12"... />

All you would need is change font-size to whatever you need

Names for grids can be confusing without more detail, as DataGridView is typically a Windows Forms name, and GridView is typically an ASP.NET name.

If it is windows as TheLearnedOne indicated, then this link would do:

http://stackoverflow.com/questions/64041/winform-datagridview-font-size

Im working with windows forms

If you set the Font property for the DataGridView, then it should apply to all the elements (headers, cells, etc.).  If you cell the Font property for a column, then it should just apply to the cells.

You can also handle the CellFormatting or CellPainting event handlers, and do special formatting for the DataGridView.

but what about specific rows at a time example

I have a list of invoices invoices 0-29 days old are black, 30-59 are blue, 60-89 yellow, 90+ red