Based on No-Title theme by jeansch
Titlebars are not really useful! Especially on 1280x800 or less screens :)
This theme fits any GTK theme using its colors.
It is a bit thiner than No-Title and maximized windows have reduced decorations. I left some decoration though cause on some GTK themes window could blend with the top or the bottom panel. If you want to get rid of all decorations in maximized state, you may change all non-zero numbers to zero in frame_geometry "maximized" section.
Some tips for those who is not very familiar with titleless UI:
You may move window by its any part while holding Alt.
In any GTK theme you may add attribute "GtkMenuBar::window-dragging = 1" to the main style section to use menubar as a titlebar.
You may use ALT+middle_mouse_button for resizing window.