This is a theme for the micro editor, based off of the excellent theme of the same name by Martin Haesler. The colors are not 1-to-1 because of the limitations of 256-color terminals and micro's syntax highlighting engine, but it is very close.
To install, CtrlE and type:
> plugin install sunny-day-theme
Or download the file sunny-day.micro and place in ~/.config/micro/colorschemes.