Dynamic scrollable region?

[Quivis]

Hello,

I have this idea for a "normal" css layout, header, scrollable area,
footer, but I want the footer "static", in the sense that it should stay
at the bottom of the window, and have the same width, no matter what
height or width the browser window is.

I've tried the following, but neihter Firefox, nor IE6, wants anything
to do with it:

/* font formatting etc. intentionally left out for brevity */

..lpart {
float: left;
width: 33%;
height: 33%;
/* height: 33em; <- this works */
overflow: auto;
}

..mpart {
float: right;
width: 33%;
height: 33%;
/* height: 33em; <- this works */
overflow: auto;
}

/* float and width not set, since this is the last of the three */
..rpart {
height: 33%;
/* height: 33em; <- this works */
overflow: auto;
}

I would want to construct those scrollable regions such, that their
height is changed by the browser window's vertical size, and the footer
should always stay put at the bottom of the window. Footer width should
follow browser's width, its height should be the same.

Using em values, works, sort of, the scrollable areas' vertical sizes
change when the font size changes, which is not exactly what I'd like to
do.

Is what I want to do even possible?

Let me know if I need to explain my problem further.

TIA for any advice.
Q.
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