We've already combined color functions in the earlier mixin near the beginning of this chapter. However, the process for combining functions perhaps bears repeating with an example.

Need a 0.7 alpha layer on an RGBA color that's a 30 percent mix of two colors? The following code describes how you'd do that:

&:nth-child(9) a {
  background-color: rgba((mix($color1,$color2,60%)),.7);
}

And the following screenshot is the result in the browser (note that, a repeating background image has been added to the body to demonstrate the alpha channel of the color):

The syntax for combining color functions does look intimidating at first, but once you've started to adjust colors in this manner you'll find it saves a lot of time. No need to open color pickers. Instead, with Sass and Compass, we can test colors directly in the browser.