// TODO from here
(details to document:)
3 locations for theme definitions: * global configuration = global theme * configuration in subdir overrides global theme * navigation.md
theme in config.json > priority navigation.md - reasons: mdwiki compatible, setting in navigation can be kept for mdwiki, in config.json can use advanced Up definition, when Up and mdwiki are used both for some reason
The place to add your theme definition is the navigation.md, which like this allows one different theme wherever you have structured your documents in separate directories.