How to develop a colour scheme for the Vector Skin on MediaWiki
Vector is one of several skins included with MediaWiki and has an advantage over other skins because there exists an Extension which enables collapsible menus.
As installed, however, Vector is rather bland. The colour scheme used here is, by contrast gaudy and not recommended...
This MediaWiki site has been created specifically to demonstrate how to assign background colours to each part of the Vector skin interface.
The weird colour theme therefore has a purpose, and is developed through a series of articles beginning here: Vector Colour Theme.
The series ends with a list of Resources including links to a few sites offering guides on how to select a pleasant colour scheme. The Vector Colour Theme series, however, is designed to show how to make the CSS changes to a MediaWiki skin, which is pre-requisite to implementing an effective colour theme.
I hope it is useful,