How to position a bar to the bottom

I have a masterpage that has a header section, upper horizontal menu bar and lower horizontal menu bar. Is there a way I can make the lower bar position so that it is always at the bottom of the page?

I also want to control the center content (child page) so that it doesn’t cause the page to have a scroll bar. I would prefer the center section to have its own scroll bar.

Thanks
Rut

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