Aisleriot toolbar icon spacing with gtk3 - possible bug?

[golinux <golinux riseup net>]

I am re-theming Xfce (gtkrc and gtk.css) and found a possible bug with 
the Aisleriot toolbar icon spacing.  The toolbar displays as it always 
has with gtk2 (gtk2.png) but with gtk3 (gtk3.png) the icon spacing is 
ignored.  I am just finding my way around the gtk.css file so not clear 
whether the problem lies there or with Aisleriot gtk3 compatibility.   
All Xfce gtk3 compatible themes display this problem and a friend said 
it is also happening on Albatross and Greybird Mac.  Any thoughts about 
how to track this down would be appreciated.

golinux

Attachment: gtk2.png
Description: PNG image

Attachment: gtk3.png
Description: PNG image