Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.2)
// Compass (v1.0.0.alpha.17)
// ----

@mixin compliment-me($color-base) {
  @if lightness($color-base) >= 51% {  
    background-color: #000000;  
  } @else if lightness($color-base) >= 30%  {
    background-color: #333333;
  } @else {  
    background-color: #ffffff;  
  }
}
.intro {
  @include compliment-me(#ffffff);
}

.body {
  @include compliment-me(#777777);
}

.sidebar {
  @include compliment-me(#000000);
}

SassMeister-output.css

.intro {
  background-color: #000000;
}

.body {
  background-color: #333333;
}

.sidebar {
  background-color: #ffffff;
}