CSD and SSD Window Control Buttons CSS Call Names

I have Fedora 27 Workstation and have Adwaita, the default theme, set. I enabled the minimize, maximize buttons which was by default disabled / not shown, I then noticed that CSDs (GTK3) and SSDs (GTK2) have different proportions and they simply don’t consistently match up with each other. My problem is I do not know what the CSS call names are for the window control buttons for both the GTK3 and GTK2 apps hence I cannot adjust (via gtk.css).

I plan to do the modification via a ~/.config/gtk-3.0/gtk.css file, so no gresource extraction is necessary.

Also if I can add a few more. Chromium seems to compress its window control buttons when maximizing it. I’ve seen themes that prevents this, resulting in a more “consistent” UI feel in my opinion, once again, I do not know how to call the window control buttons so I don’t know how to adjust the styles. I kinda want to match the proportion of the SSDs to Chromium when maximized.

How do I do all of these?

… and one last question, where do I learn to theme GTK?

Thanks you~

for gtk3-csd see https://stackoverflow.com/questions/22069839/how-to-theme-the-header-bar-close-button-in-gtk3/48390419#48390419
for gtk2 and gtk3 apps which use the system decorations there are no gtk button definitions; instead, it’s the window manager which defines the buttons. for the xfwm4 window manager you have a quick doc here: https://wiki.xfce.org/howto/xfwm4_theme (i don’t know about the others)
finally, you can check out what i did in my theme here https://www.xfce-look.org/p/1191436/ (look inside the ‘Xfce Evolution/xfwm4’ folder for the system decoration buttons and inside the ‘Xfce Evolution/gtk3/widgets.css’ file for the gtk3-csd code)