Question

How to make active(selected) link item bold when using asp.net Menu control ?

Answer 1

You can just use the styles of the Menu control:

    <asp:Menu ID="Menu1" DataSourceID="mySiteMap" runat="server" 
        Orientation="Horizontal" RenderingMode="Table" 
        StaticSubMenuIndent="16px">
        <StaticSelectedStyle Font-Bold="True" />
    </asp:Menu>

This is the result: