how do i make an element's width or height 100% of the parent's available space width/height? using height: 100%; in ie doesnt do anything and in ff makes it the height of the window. auto doesnt work ;<

(i'm doing this for a floating element)

edit: 1em doesnt work either...

here's the site: http://ssd.sc47.info/other/site1/

i need to make the sidebar go all the way down

edit: also, does it look the same in ie6?

Works fine in Opera 9 and IE 7.

also, can i somehow make the png hack for ie6 apply to backgrounds? it works fine with regular images