It looks like that GTK fails to get a color value from the theme. It also happens with Zukitwo.
I cannot find any error in the theme files. Even if there are errors, CSS errors should be ignored. At least that's the expected behavior. So I guess, it's rather a bug in GTK or gnome-system-log. I cannot confirm though.
Anyways, I'm now on GTK3.10 and the bug doesn't happen. So the bug might be a regression in GTK3.8 and it has been fixed in GTK3.10.
It looks like that GTK fails to get a color value from the theme. It also happens with Zukitwo.
I cannot find any error in the theme files. Even if there are errors, CSS errors should be ignored. At least that's the expected behavior. So I guess, it's rather a bug in GTK or gnome-system-log. I cannot confirm though.
Anyways, I'm now on GTK3.10 and the bug doesn't happen. So the bug might be a regression in GTK3.8 and it has been fixed in GTK3.10.