31879317.less

// see also http://codepen.io/seven-phases-max/pen/GJeKBz?editors=110

@alt-color: extract(
    lighten(@color, 25%) darken(@color, 25%),
    round(1 + lightness(@color) / 100));

a {
   @color: red;
    color: @alt-color;
}

b {
   @color: blue;
    color: @alt-color;
}

c {
   @color: darkgreen;
    color: @alt-color;
}

d {
   @color: black;
    color: @alt-color;
}

e {
   @color: white;
    color: @alt-color;
}

// etc.

// unused variable, it's required for lazy-evaluation in rulesets above
// don't bother about it, it is used only to make the example shorter
@color: #123;