postcss-utilities is a PostCSS plugin that have the most used mixins, shortcuts and helpers to use as 
@util rules in yours stylesheets.
Playground
Getting started
1. Install PostCSS and the plugin via npm:
npm install postcss postcss-utilities
2. Choose your runner
You can use a PostCSS runner or use directly PostCSS API. Choose your favorite runner:
3. Read the docs and start to use @util
Examples:
.cfx {
    @util clearfix;
}
.rounded-top {
    @util border-top-radius(4px);
}
@util no-hover {
    .box {
        background-color: #666;
    }
}.cfx:after {
    content: '';
    display: block;
    clear: both;
}
.rounded-top {
    border-top-left-radius: 4px;
    border-top-right-radius: 4px;
}
.no-hover .box {
    background-color: #666;
}