Disclaimer: Not sure if non-existent feature (the colour of the title bar is not meant to be changed) or a bug
Flat-Plat Version: v20170605
GTK+ 3 version: 3.22.15
Distribution: Manjaro (rolling release)
Desktop environment: Gnome 3.24.2
Related application: So far Pinta and Atom editor
blue_grey to greenI am not so sure what is going on here. At first I thought that you might somewhere hard coded the blue_grey somewhere, but I have no idea on how to create/assess a theme, hence making troubleshooting relating scss files difficult.
Confusion also hardens when some applications abide with the colour change without any issues (refer Terminal screenshot below. Transmission bittorrent client is also not affected)
I am also suspecting that there would be also other applications with this issue, since this is a general flaw.
Nautilus with correctly applied title bar colour

Terminal with menu bar follows the title bar colour

Pinta with menu bar not following the title bar colour

Atom with menu bar the same like Pinta

Thank you for the clear report.
This problem is because Pinta and Atom are GTK2 based apps.
Terminal is a GTK3 app, so it can be changed the colors via SCSS/CSS. However, in order to change the colors of the GTK2 apps, you need to edit inside src/gtk-2.0/ directory.
For example, to change the GTK2 menu bar color, simply open src/gtk-2.0/gtkrc and change the #455A64 string. 馃槂
Thank you! Fixed this on the spot, and learnt something new 馃槆 Sorry for the report - I thought it was a bug
@TechnoSparks It鈥檚 all right :)