Gemini is a "skin" created for PmWiki by Hans Bracker. Maybe "face" would be a better name, since it is what you are facing here: the appearance in form of colours, fonts and borders used, the specific layout of the page and its navigational aids, and the functionality of buttons and links employed therein.
`Gemini can show many different faces, and it is highly customisable and changable in its looks and functions. If Style Options are enabled you can choose from a number of styles for colours, fonts and layouts, for your own use, without affecting others.
`Gemini is under constant development. You can find detailed information on the Pmwiki website at Cookbook:GeminiSkin or the author's website at softflow.co.uk.
This page may have a more recent version on pmwiki.org: PmWiki:GeminiSkin, and a talk page: PmWiki:GeminiSkin-Talk.