How to change the font color of JavaScript confirm confirmation box

hi 

I used linkbutton in gridview that when users click on it, delete data from database but before deleting data it shows shows confirm error...

below is code:

 <asp:LinkButton ID="lnkRemove" runat="server" CommandArgument = '<%# Eval("ID")%>' 
                 OnClientClick = "return confirm('Do you want to delete this Item?')"
                Text = " DELETE " OnClick = "DeleteCustomer" CssClass="linkGV" Width="45px"></asp:LinkButton>

I want change confirm message's font and color How I can do it?

Best Regards

Neda