The dashed line on new Atahualpa does not seem to be the same as the old one - where page menu (along top) apperas more like marching ants (marquee), rather than the simple dashed lines that border the header and sidebar regions. Could it be that a doubled dash is being defined that is causing this to look thicker than it used to be?
Also - where can we style fonts in the admin pages besides the link/post page? I presume this can be set to anything we like in your actuall css file(s) but I had imagined font is a natural thing to want to tweak...