CSS1: % of window height
So far as I can see, there is no way in CSS1 to size or position an
element vertically relative to the browser window or frame height.
In the current spec, percentage values 'refer to parent element's
width' for margins and padding, and are 'N/A' for height. Consequently,
vertical margins specified with percentage values
change with window width -- widening a window has the effect
of increasing paragraph spacing.
I believe it would be far more useful to have percentage values for
vertical measurements refer to the window or frame height. That way,
replaced elements could be sized to fill a percentage of a window or
frame in the vertical dimension, and text could be positioned to always
appear initially in a general area of the window or frame.
In a recent experiment, I wanted an image to appear centered in the
window and a line of text to appear at the bottom of the window however
the window was sized vertically. If percentage values referred to
window height this would be doable.