I posted that link so you could see that 100% height is a well know issue in css in that it does not work very well. My intention was that you would google that some more because there are lots of better resources on the web for css discussions and help. you can look for more strategies or solutions to the height problem you are having. Maybe someone else here can help you but it is much more likely you will find an answer elsewhere.
At the end of the day, mojoPortal delivers html and css to the browser and the browser applies the css to the html, so there is nothing mojoPortal can do to change how css works or not. There could be conflicting rules in your css, best to use Firebug to understand what css rules are being applied.
Hope it helps,