Unfortunately, you can not change the color with
~/.config/gtk-3.0/gtk.css, or any other easy way, as you could in other widgets. If you need, you must change the source code like this:
--- /usr/lib/python2.7/dist-packages/gnome_sudoku/number_box.py~ 2012-08-14 19:45:16.000000000 +0900
+++ /usr/lib/python2.7/dist-packages/gnome_sudoku/number_box.py 2012-08-14 19:41:41.000000000 +0900
@@ -571,7 +571,7 @@
- cr.set_source_rgb(1.0, 1.0, 1.0)
+ cr.set_source_rgb(0.9, 0.9, 0.9)
0, 0, w, h,
- you can control the color with three values representing RGB; the sample diff above is changing
- This sample diff is for python 2.7. If you are using python3 as your default python, change the directory, accordingly.
- If you upgrade your
gnome-sudoku package, it will revert the change.
- The reason you can not control them with gtk.css is that they are
GtkDrawingAreas with the custom drawing method and literal rgb value (shown in the above diff).
Hope this helps.