PostCSS Gray 
PostCSS
Gray lets you use the gray() color function in CSS,
following the CSSWG
Specification.
body {
  background-color: gray(100);
  color: gray(0 / 90%);
}
/* becomes */
body {
  background-color: rgb(255,255,255);
  color: rgba(0,0,0,.9);
}
Usage
Add PostCSS Gray to your project:
npm install postcss-color-gray --save-devUse PostCSS Gray to process your CSS:
import postcssGray from 'postcss-color-gray';
postcssGray.process(YOUR_CSS /*, processOptions, pluginOptions */);Or use it as a PostCSS plugin:
import postcss from 'postcss';
import postcssGray from 'postcss-color-gray';
postcss([
  postcssGray(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);PostCSS Gray runs in all Node environments, with special instructions for:
| Node | Webpack | Create React App | Gulp | Grunt | 
|---|
Options
preserve
The preserve option determines whether the original
gray() function should be preserved or replaced. By
default, the gray() function is replaced.
By setting preserve to true, the original
gray() function is preserved.
postcssGray({ preserve: true });body {
  background-color: gray(100);
  color: gray(0 / 90%);
}
/* becomes */
body {
  background-color: gray(100);
  background-color: rgb(255,255,255);
  color: gray(0 / 90%);
  color: rgba(0,0,0,.9);
}