To achieve a high or low contrast desktop, perform the following steps:
Use the Theme
preference tool to
select the high contrast or low contrast desktop theme that you require.
Use the Desktop Background
preference
tool to customize your desktop background as follows:
Set the Desktop Wallpaper to No Wallpaper.
Set the Desktop Colors to Solid Color.
Select a background color that suits your needs.
In the Terminal
application, ensure
that the Use colors from system theme option is selected
in the Colors tabbed section of the Editing
Profile dialog.
In the gedit
application, ensure
that the Use default theme colors option is selected
in the Fonts & Colors tabbed section of the Preferences dialog.