This has been reported on Debian as bug #489767 ( http://bugs.debian.org/489767 ), against the Gtk+ port, version 1.0.1 (which is pretty much revision 34575). I haven't verified on trunk.
In nested <div>s with relative positioning, with height specified as
a percentage, an inmost top: <percentage> is ignored.
Reference: Attached HTML file
Observed behavior: The word "Caption" appears at the top.
Desired behavior: It should appear near the bottom, just above the
CSS workaround: It works if the units of "top" are changed to
pixels, or if the associated "position" is changed
to absolute, or if the parent's height is expressed
in pixels instead of a percentage.
Created attachment 22138 [details]
I think this is a duplicate of bug 14749. Mike, do you agree?
It looks very similar.
It is also fixed, so I guess this really was a duplicate.
*** This bug has been marked as a duplicate of 14749 ***