For RAP applications colors of UI components are specified in CSS files. This makes it somewhat hard to edit/change this for all components. However, for MD apps it should be possible to change basic color scheme and font face without the need to fiddle with CSS.
define color scheme via eclipse extension
calculate derived color from basic scheme (darker, lighter, saturation, etc.)
For RAP applications colors of UI components are specified in CSS files. This makes it somewhat hard to edit/change this for all components. However, for MD apps it should be possible to change basic color scheme and font face without the need to fiddle with CSS.