How to change the size of titlebar buttons?

Question

How can I change the size of titlebar/window buttons? Changing the fractional scaling to 125% causes many other problems, so I'm avoiding it.

Answer 1

I was able to accomplish this with some gtk.css styles. Note that this won't affect programs that set their own window titlebar styling, like Firefox, for example.

1. Create a file named gtk.css in ~/.config/gtk-3.0.

2. Enter this CSS code. This specific style makes the buttons more Windows-like (it removes the space to the right of the close button and makes the click targets fill the height of the window titlebar), but feel free to modify as you see fit.

   headerbar {
     padding-right: 0;
   }
   .titlebutton {
     min-width: 44px;
     min-height: 44px;
     padding: 0;
     margin: 0;
   }
   

3. Save the file, then log out and back in to apply the changes.

If you'd like to do some extended tweakage, I'd recommend poking around with GTK+ Inspector like I did: https://askubuntu.com/a/1377091/1587412