Help:Color Palettes

When you change the background of some text, it is highly recommended to define the color of the text itself even if you are going to use the default color, since someone may not be using the default colors of the Wiki and if you do not do these users can see that text wrong

And if you still want more, take a look at the color wheel. Or by here, where in addition to the hexadecimal code you also have the RGB.

Color palette, copied from Wikipedia under the terms of GNU free distribution.