Styling
Basic information
Styling in Wapanel is made using GTK CSS.
Style fileneeds to be located in ~/.config/wapanel, $XDG_CONFIG_HOME/wapanel or besides executable.
File should be named wapanel.css
GTK CSS reference
General overview - https://developer.gnome.org/gtk3/stable/chap-css-overview.html
Color names - https://gitlab.gnome.org/GNOME/gtk/-/blob/master/gtk/theme/Adwaita/_colors-public.scss
Properties - https://developer.gnome.org/gtk3/stable/chap-css-properties.html
Also, on each GTK widget reference page should be list of CSS nodes.