The standard dark Monokai theme for Notepad++ does not have YAML syntax highlighting.
The github-based dark Darcula theme has it, but not in my favorite "Sublime"-like colors.
So i changed the Darcula theme's YAML highlighting to resemble the "Sublime"-like colors and font as much as possible.
Based on gogo2's Darcula theme at: https://github.com/gogo2/npp-darcula
Copy file Darcula.xml to C:/Users/%USERNAME%/AppData/Roaming/Notepad++/themes directory.