postcss-minify-params 
Minify at-rule params with PostCSS.
@media only screen and ( min-width: 400px, min-height: 500px ) {
h2{
color:blue
}
}
@media only screen and (min-width:400px,min-height:500px) {
h2{
color:blue
}
}
Usage
postcss([ require('postcss-minify-params') ])
See PostCSS docs for examples for your environment.
MIT © Bogdan Chadkin