I noticed that text in the prev, next and up spans within the splitheader
div will flow outside the div if the fontsize is increased to a point where
the text (e.g. 'Previous: Subsubsection 4.4.1') no longer fits.
True, it can get a bit ugly.
A fix would be to add 'overflow: auto;' to the properties of
div.splitheader.
Done.
It also helps with the layout if the width of the prev, up and next spans is
set to 30% (or possibly a little bit less). This is now 15em for prev and
next, and undefined for up.
Done too.
I had to add a little padding so that the splitheader div doesn't show
scroll bars when selecting a link within it, but I think now it works
fine. Could you test if it runs for you? If you can git clone it:
http://git.savannah.gnu.org/cgit/elyxer.git/
and run in the main directory:
./make