CSS Three Column Equal Height

I'm looking to add two vertical columns to the left and right of the three column master pages (and others)
Whats the trick?

I've tried two script examples found on the net, where they use javascrpt / jquery to increase defined columns to the max size...   I tried updating the Root.Master, adding a Left column,  Right Colum, and Center Column.
( I put inside the center column:
                <nopCommerce:Header ID="ctrlHeader" runat="server" />
                <nopCommerce:HeaderMenu ID="ctrlHeaderMenu" runat="server" />
                <asp:ContentPlaceHolder ID="cph1" runat="server">
                </asp:ContentPlaceHolder>
)


In both cases the ctrlHeaderMenu grew... breaking my page.  
Anyway, do we have any examples on how to make the three column master pages be equal heights?