CSS styling issue - scrolling

[olgawild]

I'm trying to build a menu (see fiddle). I have text box which will be hidden in some cases, shown in some cases, so divs below that should adjust the position when \[code\]textbox\[/code\] is hidden. The \[code\]listitems\[/code\] div contains lot of list items. The bottom div should be at the bottom of the screen. \[code\]maindiv\[/code\]'s position should be fixed. Something with the style definition is messed up, I cannot scroll down to the last item. Any hints or pointers will be helpful. Thanks!