PNEink is a light, high-contrast theme for the gnome shell, intended for use on EInk displays. It was built specifically for the Pine64 PineNote-EInk-Tablet.
Just clone the repo inside '~/.themes'. After that you can select PNEink as shell theme in gnome-tweaks.
Clone to /usr/share/themes
In general, make sure to first modify the source css (.scss) files, and then regenerate the corresponding .css file, e.g.:
cd gnome-shell
sassc \
--style expanded \
gnome-shell.scss gnome-shell.css
The built-in debugger can help to identify entities that you want to modify:
dh_make -p pneink_1.0 --indep -c custom --copyrightfile "${PWD}"/LICENSE --createorig
$ cat debian/pneink.install
gnome-shell /usr/share/themes/pneink/
common /usr/share/themes/pneink/
gtk-3.0 /usr/share/themes/pneink/
dpkg-buildpackage -us -uc
dpkg --contents ../pneink_1.0-1_all.deb