I tried this plugin, and it seems to work with respect to the four setting options, except that an unexpected side-effect is that upon activation and saving the settings the websites' background color did not display properly. The Appearance-Background color selection remained unchanged with the custom color that I chose, however when viewed as displayed on the web, the color appeared more or less as a faded grey color - very different from my original color.
Disabling the various setting options one at a time did not help; disabling all of them did not help. Only by deactivating the plugin did the original color selection once again take effect.
I can't use this plugin until it doesn't interfere with the background color, but it otherwise seemed to work okay.